{"id":12631,"date":"2024-01-03T00:04:23","date_gmt":"2024-01-02T16:04:23","guid":{"rendered":"https:\/\/blog.iyatt.com\/?p=12631"},"modified":"2024-05-05T12:31:04","modified_gmt":"2024-05-05T04:31:04","slug":"mysql-%e5%ad%a6%e4%b9%a0%e5%9f%ba%e7%a1%80%e8%ae%b0%e5%bd%95%ef%bc%88%e7%bc%96%e8%be%91%e4%b8%ad%ef%bc%89","status":"publish","type":"post","link":"https:\/\/blog.iyatt.com\/?p=12631","title":{"rendered":"MySQL \u5b66\u4e60\u8bb0\u5f55"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_82_2 ez-toc-wrap-center counter-hierarchy ez-toc-counter ez-toc-light-blue ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title ez-toc-toggle\" style=\"cursor:pointer\">\u76ee\u5f55<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span 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ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E7%AC%A6%E5%8F%B7\" >\u7b26\u53f7<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E6%AF%94%E8%BE%83%E8%BF%90%E7%AE%97%E7%AC%A6\" >\u6bd4\u8f83\u8fd0\u7b97\u7b26<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E9%80%BB%E8%BE%91%E8%BF%90%E7%AE%97%E7%AC%A6\" >\u903b\u8f91\u8fd0\u7b97\u7b26<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#DDL\" >DDL<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E6%95%B0%E6%8D%AE%E5%BA%93%E6%93%8D%E4%BD%9C\" 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href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%A4%96%E9%94%AE%E7%BA%A6%E6%9D%9F%E7%A4%BA%E4%BE%8B\" >\u5916\u952e\u7ea6\u675f\u793a\u4f8b<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-34\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%88%9B%E5%BB%BA%E8%A1%A8%E6%97%B6%E6%B7%BB%E5%8A%A0%E5%A4%96%E9%94%AE\" >\u521b\u5efa\u8868\u65f6\u6dfb\u52a0\u5916\u952e<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-35\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E7%8E%B0%E6%9C%89%E8%A1%A8%E6%B7%BB%E5%8A%A0%E5%A4%96%E9%94%AE\" >\u73b0\u6709\u8868\u6dfb\u52a0\u5916\u952e<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-36\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%88%A0%E9%99%A4%E5%A4%96%E9%94%AE\" >\u5220\u9664\u5916\u952e<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-37\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%A4%96%E9%94%AE%E7%BA%A6%E6%9D%9F%E8%A1%8C%E4%B8%BA\" >\u5916\u952e\u7ea6\u675f\u884c\u4e3a<\/a><\/li><\/ul><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-38\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%A4%9A%E8%A1%A8%E6%9F%A5%E8%AF%A2\" >\u591a\u8868\u67e5\u8be2<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-39\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%85%B3%E7%B3%BB\" >\u5173\u7cfb<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-40\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E4%B8%80%E5%AF%B9%E4%B8%80\" >\u4e00\u5bf9\u4e00<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-41\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E4%B8%80%E5%AF%B9%E5%A4%9A\" >\u4e00\u5bf9\u591a<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-42\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%A4%9A%E5%AF%B9%E5%A4%9A\" >\u591a\u5bf9\u591a<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-43\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%86%85%E8%BF%9E%E6%8E%A5\" >\u5185\u8fde\u63a5<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-44\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%A4%96%E8%BF%9E%E6%8E%A5\" >\u5916\u8fde\u63a5<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-45\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E8%87%AA%E8%BF%9E%E6%8E%A5\" >\u81ea\u8fde\u63a5<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-46\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E8%81%94%E5%90%88%E6%9F%A5%E8%AF%A2\" >\u8054\u5408\u67e5\u8be2<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-47\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%AD%90%E6%9F%A5%E8%AF%A2%E5%B5%8C%E5%A5%97%E6%9F%A5%E8%AF%A2\" >\u5b50\u67e5\u8be2\/\u5d4c\u5957\u67e5\u8be2<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-48\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E6%A0%87%E9%87%8F%E5%AD%90%E6%9F%A5%E8%AF%A2\" >\u6807\u91cf\u5b50\u67e5\u8be2<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-49\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%88%97%E5%AD%90%E6%9F%A5%E8%AF%A2\" >\u5217\u5b50\u67e5\u8be2<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-50\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E8%A1%8C%E5%AD%90%E6%9F%A5%E8%AF%A2\" >\u884c\u5b50\u67e5\u8be2<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-51\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E8%A1%A8%E5%AD%90%E6%9F%A5%E8%AF%A2\" >\u8868\u5b50\u67e5\u8be2<\/a><\/li><\/ul><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-52\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E4%BA%8B%E5%8A%A1\" >\u4e8b\u52a1<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-53\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E7%89%B9%E6%80%A7%EF%BC%88ACID%EF%BC%89\" >\u7279\u6027\uff08ACID\uff09<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-54\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%B9%B6%E5%8F%91%E4%BA%8B%E5%8A%A1%E5%AD%98%E5%9C%A8%E7%9A%84%E9%97%AE%E9%A2%98\" >\u5e76\u53d1\u4e8b\u52a1\u5b58\u5728\u7684\u95ee\u9898<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-55\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E4%BA%8B%E5%8A%A1%E9%9A%94%E7%A6%BB%E7%BA%A7%E5%88%AB\" >\u4e8b\u52a1\u9694\u79bb\u7ea7\u522b<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-56\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%AD%98%E5%82%A8%E5%BC%95%E6%93%8E\" >\u5b58\u50a8\u5f15\u64ce<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-57\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E7%B4%A2%E5%BC%95_%E2%80%93_%E6%9F%A5%E8%AF%A2%E4%BC%98%E5%8C%96\" >\u7d22\u5f15 &#8211; \u67e5\u8be2\u4f18\u5316<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-58\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E8%AF%AD%E6%B3%95\" >\u8bed\u6cd5<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-59\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E6%80%A7%E8%83%BD%E5%88%86%E6%9E%90\" >\u6027\u80fd\u5206\u6790<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-60\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E6%9F%A5%E8%AF%A2_SQL_%E6%89%A7%E8%A1%8C%E9%A2%91%E6%AC%A1\" >\u67e5\u8be2 SQL \u6267\u884c\u9891\u6b21<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-61\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E6%85%A2%E6%9F%A5%E8%AF%A2%E6%97%A5%E5%BF%97\" >\u6162\u67e5\u8be2\u65e5\u5fd7<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-62\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#profile\" >profile<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-63\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#explain_%E6%89%A7%E8%A1%8C%E8%AE%A1%E5%88%92\" >explain \u6267\u884c\u8ba1\u5212<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-64\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E4%BD%BF%E7%94%A8\" >\u4f7f\u7528<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-65\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E7%B4%A2%E5%BC%95%E6%9C%89%E6%95%88%E6%9D%A1%E4%BB%B6_%E2%80%93_%E6%9C%80%E5%B7%A6%E5%89%8D%E7%BC%80%E6%B3%95%E5%88%99\" >\u7d22\u5f15\u6709\u6548\u6761\u4ef6 &#8211; \u6700\u5de6\u524d\u7f00\u6cd5\u5219<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-66\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E7%B4%A2%E5%BC%95%E5%A4%B1%E6%95%88%E6%83%85%E5%86%B5_1_%E2%80%93_%E7%B4%A2%E5%BC%95%E5%88%97%E8%BF%90%E7%AE%97\" >\u7d22\u5f15\u5931\u6548\u60c5\u51b5 1 &#8211; \u7d22\u5f15\u5217\u8fd0\u7b97<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-67\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E7%B4%A2%E5%BC%95%E5%A4%B1%E6%95%88%E6%83%85%E5%86%B5_2_%E2%80%93_%E8%8C%83%E5%9B%B4%E7%B4%A2%E5%BC%95\" >\u7d22\u5f15\u5931\u6548\u60c5\u51b5 2 &#8211; \u8303\u56f4\u7d22\u5f15<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-68\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E7%B4%A2%E5%BC%95%E5%A4%B1%E6%95%88%E6%83%85%E5%86%B5_3_%E2%80%93_%E6%A8%A1%E7%B3%8A%E6%9F%A5%E8%AF%A2\" >\u7d22\u5f15\u5931\u6548\u60c5\u51b5 3 &#8211; \u6a21\u7cca\u67e5\u8be2<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-69\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E7%B4%A2%E5%BC%95%E5%A4%B1%E6%95%88%E6%83%85%E5%86%B5_4_%E2%80%93_OR_%E8%BF%9E%E6%8E%A5%E7%9A%84%E6%9D%A1%E4%BB%B6\" >\u7d22\u5f15\u5931\u6548\u60c5\u51b5 4 &#8211; OR \u8fde\u63a5\u7684\u6761\u4ef6<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-70\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E7%B4%A2%E5%BC%95%E5%A4%B1%E6%95%88%E6%83%85%E5%86%B5_5_%E2%80%93_%E6%95%B0%E6%8D%AE%E5%88%86%E5%B8%83%E5%BD%B1%E5%93%8D%EF%BC%88%E4%BC%98%E5%8C%96%EF%BC%89\" >\u7d22\u5f15\u5931\u6548\u60c5\u51b5 5 &#8211; \u6570\u636e\u5206\u5e03\u5f71\u54cd\uff08\u4f18\u5316\uff09<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-71\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E7%B4%A2%E5%BC%95%E6%8F%90%E7%A4%BA\" >\u7d22\u5f15\u63d0\u793a<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-72\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E8%A6%86%E7%9B%96%E7%B4%A2%E5%BC%95\" >\u8986\u76d6\u7d22\u5f15<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-73\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%89%8D%E7%BC%80%E7%B4%A2%E5%BC%95\" >\u524d\u7f00\u7d22\u5f15<\/a><\/li><\/ul><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-74\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%85%B6%E5%AE%83%E4%BC%98%E5%8C%96\" >\u5176\u5b83\u4f18\u5316<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-75\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E6%8F%92%E5%85%A5%E4%BC%98%E5%8C%96\" >\u63d2\u5165\u4f18\u5316<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-76\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E4%BB%8E%E6%96%87%E4%BB%B6%E5%AF%BC%E5%85%A5%E6%95%B0%E6%8D%AE\" >\u4ece\u6587\u4ef6\u5bfc\u5165\u6570\u636e<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-77\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E4%B8%BB%E9%94%AE%E4%BC%98%E5%8C%96\" >\u4e3b\u952e\u4f18\u5316<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-78\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E6%8E%92%E5%BA%8F%E4%BC%98%E5%8C%96\" >\u6392\u5e8f\u4f18\u5316<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-79\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%88%86%E7%BB%84%E4%BC%98%E5%8C%96\" >\u5206\u7ec4\u4f18\u5316<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-80\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E8%A7%86%E5%9B%BE\" >\u89c6\u56fe<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-81\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%9F%BA%E6%9C%AC%E4%BD%BF%E7%94%A8\" >\u57fa\u672c\u4f7f\u7528<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-82\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E6%A3%80%E6%9F%A5%E9%80%89%E9%A1%B9\" >\u68c0\u67e5\u9009\u9879<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-83\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%AD%98%E5%82%A8%E8%BF%87%E7%A8%8B\" >\u5b58\u50a8\u8fc7\u7a0b<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-84\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E8%AF%AD%E5%8F%A5%E5%88%86%E9%9A%94%E7%AC%A6%E4%BF%AE%E6%94%B9\" >\u8bed\u53e5\u5206\u9694\u7b26\u4fee\u6539<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-85\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%9F%BA%E6%9C%AC%E4%BD%BF%E7%94%A8-2\" >\u57fa\u672c\u4f7f\u7528<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-86\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%8F%98%E9%87%8F\" >\u53d8\u91cf<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-87\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E7%B3%BB%E7%BB%9F%E5%8F%98%E9%87%8F\" >\u7cfb\u7edf\u53d8\u91cf<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-88\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E7%94%A8%E6%88%B7%E8%87%AA%E5%AE%9A%E4%B9%89%E5%8F%98%E9%87%8F\" >\u7528\u6237\u81ea\u5b9a\u4e49\u53d8\u91cf<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-89\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%B1%80%E9%83%A8%E5%8F%98%E9%87%8F\" >\u5c40\u90e8\u53d8\u91cf<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-90\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%AD%98%E5%82%A8%E8%BF%87%E7%A8%8B%E7%9A%84%E5%8F%82%E6%95%B0%E4%BC%A0%E9%80%92\" >\u5b58\u50a8\u8fc7\u7a0b\u7684\u53c2\u6570\u4f20\u9012<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-91\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E6%9D%A1%E4%BB%B6%E5%88%A4%E6%96%AD\" >\u6761\u4ef6\u5224\u65ad<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-92\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#IF\" >IF<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-93\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#CASE\" >CASE<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-94\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%BE%AA%E7%8E%AF\" >\u5faa\u73af<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-95\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#WHILE\" >WHILE<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-96\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#REPEAT\" >REPEAT<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-97\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#LOOP\" >LOOP<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-98\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E6%B8%B8%E6%A0%87%E5%92%8C%E6%9D%A1%E4%BB%B6%E5%A4%84%E7%90%86%E7%A8%8B%E5%BA%8F\" >\u6e38\u6807\u548c\u6761\u4ef6\u5904\u7406\u7a0b\u5e8f<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-99\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E5%AD%98%E5%82%A8%E5%87%BD%E6%95%B0\" >\u5b58\u50a8\u51fd\u6570<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-100\" href=\"https:\/\/blog.iyatt.com\/?p=12631\/#%E8%A7%A6%E5%8F%91%E5%99%A8\" >\u89e6\u53d1\u5668<\/a><\/li><\/ul><\/nav><\/div>\n<h1><span class=\"ez-toc-section\" id=\"%E7%8E%AF%E5%A2%83\"><\/span>\u73af\u5883<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<ul>\n<li>MySQL \u793e\u533a\u7248 8.0.35<\/li>\n<li>IDEA 2023\uff1a\u4e4b\u524d\u5b66 Kotlin \u548c Android \u5f00\u53d1\u7684\u65f6\u5019\u5b89\u88c5\u7684\uff0c\u91cc\u9762\u4e5f\u6709\u5185\u7f6e DataGrip\uff0c\u7528\u6765\u56fe\u5f62\u5316\u64cd\u4f5c\u6570\u636e\u5e93\u5f88\u65b9\u4fbf\uff0c\u4e5f\u652f\u6301 SQL \u8bed\u53e5\u63d0\u793a\uff0c\u4f5c\u4e3a\u8f85\u52a9\u5de5\u5177\u3002(<a href=\"https:\/\/blog.iyatt.com\/?p=12618\">https:\/\/blog.iyatt.com\/?p=12618<\/a>)<\/li>\n<\/ul>\n<p>\u6ce8\uff1a<\/p>\n<ul>\n<li>\u6570\u636e\u5e93\u4e2d\u7684\u5173\u952e\u5b57\u7528\u5927\u5199\u6216\u8005\u5c0f\u5199\u90fd\u884c\uff0c\u4f46\u662f\u4e00\u822c\u5e94\u8be5\u662f\u7528\u5927\u5199\u6bd4\u8f83\u89c4\u8303\uff0c\u8bfb\u4ee3\u7801\u7684\u65f6\u5019\u4e00\u773c\u660e\u4e86\u3002\u81f3\u4e8e\u81ea\u5df1\u547d\u540d\u90e8\u5206\u7684\uff0c\u50cf\u6570\u636e\u5e93\u540d\u3001\u8868\u540d\u7b49\u7b49\uff0c\u5728 Windows \u4e0b\u5927\u5c0f\u5199\u7b49\u540c\uff0cLinux \u4e0b\u9ed8\u8ba4\u662f\u4f1a\u533a\u5206\u5927\u5c0f\u5199\u7684\u3002MySQL \u5b9e\u9645\u5e94\u7528\u4e2d\u5e94\u8be5\u8fd8\u662f\u5728 Linux \u670d\u52a1\u5668\u4e0a\u4e3a\u4e3b\uff0c\u5f00\u59cb\u5b66\u4e60\u7684\u65f6\u5019\u8fd8\u662f\u89c4\u8303\u5927\u5c0f\u5199\u6bd4\u8f83\u597d\uff0c\u5f62\u6210\u4e60\u60ef\u3002<\/li>\n<li>SQL \u8bed\u53e5\u7ed3\u675f\u4f7f\u7528\u5206\u53f7\u3002<\/li>\n<li>\u4e0b\u9762\u793a\u4f8b\u7528\u6cd5\u4e2d\u4f7f\u7528\u4e2d\u62ec\u53f7\u7684\u8bed\u53e5\u4ee3\u8868\u53ef\u9009\u3002<\/li>\n<\/ul>\n<h1><span class=\"ez-toc-section\" id=\"%E6%95%B0%E6%8D%AE%E7%B1%BB%E5%9E%8B\"><\/span>\u6570\u636e\u7c7b\u578b<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<h2><span class=\"ez-toc-section\" id=\"%E5%AD%97%E7%AC%A6%E4%B8%B2%E7%B1%BB%E5%9E%8B\"><\/span>\u5b57\u7b26\u4e32\u7c7b\u578b<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|}\n\\hline\n\u7c7b\u578b &amp; \u63cf\u8ff0 \\\\\n\\hline\nCHAR &amp; \u7eaf\u6587\u672c\u5b57\u7b26\u4e32\uff0c\u5b57\u7b26\u4e32\u957f\u5ea6\u662f\u56fa\u5b9a\u7684\u3002\u5f53\u5b9e\u9645\u5b57\u6bb5\u5185\u5bb9\u5c0f\u4e8e\u5b9a\u4e49\u7684\u957f\u5ea6\u65f6\uff0cMySQL \u4f1a\u7528\u7a7a\u767d\u7a7a\u767d\u7b26\u597d\u8865\u8db3\u3002 \\\\\n\\hline\nVARCHAR &amp; \u7eaf\u6587\u672c\u5b57\u7b26\u4e32\uff0c\u5b57\u7b26\u4e32\u957f\u5ea6\u662f\u53ef\u53d8\u7684\u3002\\\\\n\\hline\nBINARY &amp; \u4e8c\u8fdb\u5236\u5b57\u7b26\u4e32\uff0c\u5b57\u7b26\u4e32\u957f\u5ea6\u662f\u56fa\u5b9a\u7684\u3002 \\\\\n\\hline\nVARBINARY &amp; \u4e8c\u8fdb\u5236\u5b57\u7b26\u4e32\uff0c\u5b57\u7b26\u4e32\u957f\u5ea6\u662f\u53ef\u53d8\u7684\u3002\\\\\n\\hline\nTINYTEXT &amp; \u4e8c\u8fdb\u5236\u5b57\u7b26\u4e32\uff0c\u6700\u5927\u4e3a 255 \u4e2a\u5b57\u8282\u3002\\\\\n\\hline\nTEXT &amp; \u4e8c\u8fdb\u5236\u5b57\u7b26\u4e32\uff0c\u6700\u5927\u4e3a 65K\u3002\\\\\n\\hline\nMEDIUMTEXT &amp; \u4e8c\u8fdb\u5236\u5b57\u7b26\u4e32\uff0c\u6700\u5927\u4e3a 16M\u3002 \\\\\n\\hline\nLONGTEXT &amp; \u4e8c\u8fdb\u5236\u5b57\u7b26\u4e32\uff0c\u6700\u5927\u4e3a 4G\u3002\\\\\n\\hline\nENUM &amp; \u679a\u4e3e\uff1b\u6bcf\u4e2a\u5217\u503c\u53ef\u4ee5\u5206\u914d\u4e00\u4e2a ENUM \u6210\u5458\u3002 \\\\\n\\hline\nSET &amp; \u96c6\u5408\uff1b\u6bcf\u4e2a\u5217\u503c\u53ef\u4ee5\u5206\u914d\u96f6\u4e2a\u6216\u591a\u4e2a SET \u6210\u5458\u3002 \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<h2><span class=\"ez-toc-section\" id=\"%E6%95%B0%E5%AD%97%E7%B1%BB%E5%9E%8B\"><\/span>\u6570\u5b57\u7c7b\u578b<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|}\n\\hline\n\u7c7b\u578b &amp; \u63cf\u8ff0 \\\\\n\\hline\nTINYINT &amp; \u4e00\u4e2a\u975e\u5e38\u5c0f\u7684\u6574\u6570\uff0c\u6700\u5927\u4e3a 1 \u4e2a\u5b57\u8282\u3002\\\\\n\\hline\nSMALLINT &amp; \u4e00\u4e2a\u5c0f\u6574\u6570\uff0c\u6700\u5927\u4e3a 2 \u4e2a\u5b57\u8282\u3002\\\\\n\\hline\nMEDIUMINT &amp; \u4e00\u4e2a\u4e2d\u7b49\u5927\u5c0f\u7684\u6574\u6570\uff0c\u6700\u5927\u4e3a 3 \u4e2a\u5b57\u8282\u3002\\\\\n\\hline\nINT &amp; \u6807\u51c6\u6574\u6570\uff0c\u6700\u5927\u4e3a 4 \u4e2a\u5b57\u8282\u3002\\\\\n\\hline\nBIGINT &amp; \u4e00\u4e2a\u5927\u6574\u6570\uff0c\u6700\u5927\u4e3a 8 \u4e2a\u5b57\u8282\u3002\\\\\n\\hline\nDECIMAL &amp; \u4e00\u4e2a\u5b9a\u70b9\u6570\u3002\\\\\n\\hline\nFLOAT &amp; \u5355\u7cbe\u5ea6\u6d6e\u70b9\u6570\uff0c\u6700\u5927\u4e3a 4 \u4e2a\u5b57\u8282\u3002\\\\\n\\hline\nDOUBLE &amp; \u53cc\u7cbe\u5ea6\u6d6e\u70b9\u6570\uff0c\u6700\u5927\u4e3a 8 \u4e2a\u5b57\u8282\u3002\\\\\n\\hline\nBIT &amp; \u6309\u4f4d\u5b58\u50a8\u3002\\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<h2><span class=\"ez-toc-section\" id=\"%E5%B8%83%E5%B0%94%E7%B1%BB%E5%9E%8B\"><\/span>\u5e03\u5c14\u7c7b\u578b<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>MySQL \u6ca1\u6709\u5185\u7f6e\u7684\u5e03\u5c14\u7c7b\u578b\uff0c\u4f46\u662f\u6709 BOOLEAN \u548c BOOL \u5173\u952e\u5b57\uff0c\u5185\u90e8\u5f53\u505a TINYINT \u7c7b\u578b\u5904\u7406\uff0cTRUE \u5bf9\u5e94 1\uff0cFALSE \u5bf9\u5e94 0\u3002<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E6%97%A5%E6%9C%9F%E5%92%8C%E6%97%B6%E9%97%B4%E7%B1%BB%E5%9E%8B\"><\/span>\u65e5\u671f\u548c\u65f6\u95f4\u7c7b\u578b<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|}\n\\hline\n\u7c7b\u578b &amp; \u63cf\u8ff0 \\\\\n\\hline\nDATE &amp; CCYY-MM-DD \u683c\u5f0f\u7684\u65e5\u671f\u503c \\\\\n\\hline\nTIME &amp; hh:mm:ss \u683c\u5f0f\u7684\u65f6\u95f4\u503c \\\\\n\\hline\nDATETIME &amp; CCYY-MM-DD hh:mm:ss \u683c\u5f0f\u7684\u65e5\u671f\u548c\u65f6\u95f4\u503c \\\\\n\\hline\nTIMESTAMP &amp; CCYY-MM-DD hh:mm:ss \u683c\u5f0f\u7684\u65f6\u95f4\u6233\u503c \\\\\n\\hline\nYEAR &amp; CCYY \u6216 YY \u683c\u5f0f\u7684\u5e74\u4efd\u503c \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<h2><span class=\"ez-toc-section\" id=\"%E4%BA%8C%E8%BF%9B%E5%88%B6%E7%B1%BB%E5%9E%8B\"><\/span>\u4e8c\u8fdb\u5236\u7c7b\u578b<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|}\n\\hline\n\u7c7b\u578b &amp; \u63cf\u8ff0 \\\\\n\\hline\nTINYBLOB &amp; \u6700\u5927\u4e3a 255 \u4e2a\u5b57\u8282\u3002\\\\\n\\hline\nBLOB &amp; \u6700\u5927\u4e3a 65K\u3002\\\\\n\\hline\nMEDIUMBLOB &amp; \u6700\u5927\u4e3a 16M\u3002\\\\\n\\hline\nLONGBLOB &amp; \u6700\u5927\u4e3a 4G\u3002\\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<h2><span class=\"ez-toc-section\" id=\"%E7%A9%BA%E9%97%B4%E6%95%B0%E6%8D%AE%E7%B1%BB%E5%9E%8B\"><\/span>\u7a7a\u95f4\u6570\u636e\u7c7b\u578b<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|}\n\\hline\n\u7c7b\u578b &amp; \u63cf\u8ff0 \\\\\n\\hline\nGEOMETRY &amp; \u4efb\u4f55\u7c7b\u578b\u7684\u7a7a\u95f4\u503c \\\\\n\\hline\nPOINT &amp; \u4f7f\u7528\u6a2a\u5750\u6807\u548c\u7eb5\u5750\u6807\u8868\u793a\u7684\u4e00\u4e2a\u70b9 \\\\\n\\hline\nLINESTRING &amp; \u4e00\u6761\u66f2\u7ebf\uff08\u4e00\u4e2a\u6216\u591a\u4e2a POINT \u503c\uff09 \\\\\n\\hline\nPOLYGON &amp; \u4e00\u4e2a\u591a\u8fb9\u5f62 \\\\\n\\hline\nGEOMETRYCOLLECTION &amp; GEOMETRY \u503c\u7684\u96c6\u5408 \\\\\n\\hline\nMULTILINESTRING &amp; LINESTRING \u503c\u7684\u96c6\u5408 \\\\\n\\hline\nMULTIPOINT &amp; POINT \u503c\u7684\u96c6\u5408 \\\\\n\\hline\nMULTIPOLYGON &amp; POLYGON \u503c\u7684\u96c6\u5408 \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<h2><span class=\"ez-toc-section\" id=\"JSON_%E7%B1%BB%E5%9E%8B\"><\/span>JSON \u7c7b\u578b<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>MySQL \u4ece 5.7.8 \u5f00\u59cb\u652f\u6301 JSON \u6570\u636e\u7c7b\u578b\u3002<\/p>\n<h1><span class=\"ez-toc-section\" id=\"%E7%AC%A6%E5%8F%B7\"><\/span>\u7b26\u53f7<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<h2><span class=\"ez-toc-section\" id=\"%E6%AF%94%E8%BE%83%E8%BF%90%E7%AE%97%E7%AC%A6\"><\/span>\u6bd4\u8f83\u8fd0\u7b97\u7b26<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|}\n\\hline\n\u7b26\u53f7 &amp; \u63cf\u8ff0 \\\\\n\\hline\n\\gt &amp; \u5927\u4e8e \\\\\n\\hline\n\\gt= &amp; \u5927\u4e8e\u7b49\u4e8e \\\\\n\\hline\n\\lt &amp; \u5c0f\u4e8e \\\\\n\\hline\n\\lt= &amp; \u5c0f\u4e8e\u7b49\u4e8e \\\\\n\\hline\n= &amp; \u7b49\u4e8e \\\\\n\\hline\n\\lt\\gt \u6216 != &amp; \u4e0d\u7b49\u4e8e \\\\\n\\hline\nBETWEEN ... AND ... &amp; \u5728\u67d0\u4e2a\u8303\u56f4\u4e4b\u5185\uff08\u542b\u6700\u5c0f\u548c\u6700\u5927\u503c\uff09 \\\\\n\\hline\nIN\\ (...) &amp; \u5728\u5217\u8868\u4e2d\u7684\u503c\uff08\u591a\u9009\u4e00\uff09\\\\\n\\hline\nLIKE\\ \u5360\u4f4d\u7b26 &amp; \u6a21\u7cca\u5339\u914d\uff08\\_\u5339\u914d\u5355\u4e2a\u5b57\u7b26\uff0c\\% \u5339\u914d\u4efb\u610f\u591a\u4e2a\u5b57\u7b26\uff09\\\\\n\\hline\nIS NULL &amp; \u4e3a\u7a7a \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<h2><span class=\"ez-toc-section\" id=\"%E9%80%BB%E8%BE%91%E8%BF%90%E7%AE%97%E7%AC%A6\"><\/span>\u903b\u8f91\u8fd0\u7b97\u7b26<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|}\n\\hline\n\u7b26\u53f7 &amp; \u63cf\u8ff0 \\\\\n\\hline\nAND \u6216 \\&amp;\\&amp; &amp; \u548c\uff0c\u591a\u4e2a\u6761\u4ef6\u540c\u65f6\u6210\u7acb \\\\\n\\hline\nOR \u6216 || &amp; \u6216\uff0c\u4efb\u610f\u4e00\u4e2a\u6761\u4ef6\u6210\u7acb \\\\\n\\hline\nNOT \u6216 | &amp; \u5426 \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<h1><span class=\"ez-toc-section\" id=\"DDL\"><\/span>DDL<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>Data Definition Language\uff0c\u6570\u636e\u5b9a\u4e49\u8bed\u8a00<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E6%95%B0%E6%8D%AE%E5%BA%93%E6%93%8D%E4%BD%9C\"><\/span>\u6570\u636e\u5e93\u64cd\u4f5c<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u67e5\u8be2\u6240\u6709\u6570\u636e\u5e93<\/p>\n<pre><code class=\"language-mysql\">SHOW DATABASES;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704248747121.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 234px; --smush-placeholder-aspect-ratio: 234\/208;\" \/><\/p>\n<p>\u521b\u5efa\u6570\u636e\u5e93<\/p>\n<pre><code class=\"language-mysql\">CREATE DATABASE [IF NOT EXISTS] \u6570\u636e\u5e93\u540d [DEFAULT CHARSET \u5b57\u7b26\u96c6] [COLLATE \u6392\u5e8f\u89c4\u5219]<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704249165663.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 328px; --smush-placeholder-aspect-ratio: 328\/278;\" \/><\/p>\n<p>\u4f7f\u7528\u6570\u636e\u5e93<\/p>\n<pre><code class=\"language-mysql\">USE \u6570\u636e\u5e93\u540d<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704249258338.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 218px; --smush-placeholder-aspect-ratio: 218\/52;\" \/><\/p>\n<p>\u67e5\u8be2\u5f53\u524d\u4f7f\u7528\u7684\u6570\u636e\u5e93<\/p>\n<pre><code class=\"language-mysql\">SELECT DATABASE();<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704249315034.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 256px; --smush-placeholder-aspect-ratio: 256\/151;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E8%A1%A8%E6%93%8D%E4%BD%9C\"><\/span>\u8868\u64cd\u4f5c<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u8868\u64cd\u4f5c\u524d\u8981\u5148\u901a\u8fc7 USE \u6307\u5b9a\u4f7f\u7528\u7684\u6570\u636e\u5e93<\/p>\n<p>\u521b\u5efa\u8868<\/p>\n<pre><code>CREATE TABLE \u8868\u540d (\n\u5b57\u6bb51 \u5b57\u6bb51\u7684\u7c7b\u578b [COMMENT \u5b57\u6bb51\u7684\u6ce8\u91ca],\n\u5b57\u6bb52 \u5b57\u6bb52\u7684\u7c7b\u578b [COMMENT \u5b57\u6bb52\u7684\u6ce8\u91ca],\n\u5b57\u6bb53 \u5b57\u6bb53\u7684\u7c7b\u578b [COMMENT \u5b57\u6bb53\u7684\u6ce8\u91ca],\n......\n);<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704261866933.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 423px; --smush-placeholder-aspect-ratio: 423\/122;\" \/><\/p>\n<p>\u67e5\u770b\u5f53\u524d\u6570\u636e\u5e93\u4e2d\u7684\u6240\u6709\u8868<\/p>\n<pre><code class=\"language-mysql\">SHOW TABLES;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704261917084.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 251px; --smush-placeholder-aspect-ratio: 251\/150;\" \/><\/p>\n<p>\u67e5\u770b\u8868\u7ed3\u6784<\/p>\n<pre><code class=\"language-mysql\">DESC \u8868\u540d<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704261975933.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 505px; --smush-placeholder-aspect-ratio: 505\/184;\" \/><\/p>\n<p>\u67e5\u770b\u521b\u5efa\u8868\u7684\u8bed\u53e5<\/p>\n<pre><code class=\"language-mysql\">SHOW CREATE TABLE \u8868\u540d<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704262044645.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 623px; --smush-placeholder-aspect-ratio: 623\/380;\" \/><\/p>\n<p>\u8868\u6dfb\u52a0\u5b57\u6bb5<\/p>\n<pre><code class=\"language-mysql\">ALTER TABLE \u8868\u540d ADD \u5b57\u6bb5 \u7c7b\u578b [COMMENT \u6ce8\u91ca] [\u7ea6\u675f]<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704262422315.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 622px; --smush-placeholder-aspect-ratio: 622\/273;\" \/><\/p>\n<p>\u8868\u4fee\u6539\u5b57\u6bb5\u7c7b\u578b<\/p>\n<pre><code class=\"language-mysql\">ALTER TABLE \u8868\u540d MODIFY \u5b57\u6bb5 \u65b0\u7c7b\u578b [COMMENT \u6ce8\u91ca] [\u7ea6\u675f]<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704262561922.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 518px; --smush-placeholder-aspect-ratio: 518\/286;\" \/><\/p>\n<p>\u8868\u4fee\u6539\u5b57\u6bb5\u540d\u548c\u5b57\u6bb5\u7c7b\u578b<\/p>\n<pre><code class=\"language-mysql\">ALTER TABLE \u8868\u540d CHANGE \u65e7\u5b57\u6bb5 \u65b0\u5b57\u6bb5 \u65b0\u7c7b\u578b [COMMENT \u6ce8\u91ca] [\u7ea6\u675f<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704262818022.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 718px; --smush-placeholder-aspect-ratio: 718\/287;\" \/><\/p>\n<p>\u8868\u5220\u9664\u5b57\u6bb5<\/p>\n<pre><code class=\"language-mysql\">ALTER TABLE DROP \u8868\u540d<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704263550344.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 509px; --smush-placeholder-aspect-ratio: 509\/257;\" \/><\/p>\n<p>\u4fee\u6539\u8868\u540d<\/p>\n<pre><code class=\"language-mysql\uff1b\">ALTER TABLE \u8868\u540d RENAME TO \u65b0\u8868\u540d<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704264063728.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 437px; --smush-placeholder-aspect-ratio: 437\/67;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704264099426.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 252px; --smush-placeholder-aspect-ratio: 252\/140;\" \/><\/p>\n<p>\u5220\u9664\u8868<\/p>\n<pre><code class=\"language-mysql\">DROP TABLE [IF EXISTS] \u8868\u540d<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704264267451.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 341px; --smush-placeholder-aspect-ratio: 341\/112;\" \/><\/p>\n<p>\u5220\u9664\u8868\u4e2d\u7684\u6240\u6709\u6570\u636e\u4f46\u662f\u4fdd\u7559\u7ed3\u6784<\/p>\n<pre><code class=\"language-mysql\">TRUNCATE TABLE \u8868\u540d<\/code><\/pre>\n<h1><span class=\"ez-toc-section\" id=\"DML\"><\/span>DML<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>Data Manipulation Language\uff0c\u6570\u636e\u64cd\u4f5c\u8bed\u8a00<\/p>\n<p>\u7ed9\u6307\u5b9a\u5b57\u6bb5\u6dfb\u52a0\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">INSERT INTO \u8868\u540d (\u5b57\u6bb51, \u5b57\u6bb52,...) VALUES (\u503c1, \u503c2,...)<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704292692369.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 530px; --smush-placeholder-aspect-ratio: 530\/246;\" \/><\/p>\n<p>\u7ed9\u5168\u90e8\u5b57\u6bb5\u6dfb\u52a0\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">INSERT INTO \u8868\u540d VALUES \uff08\u503c1, \u503c2, ...);<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704292826700.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 471px; --smush-placeholder-aspect-ratio: 471\/72;\" \/><\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704293045935.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 820px; --smush-placeholder-aspect-ratio: 820\/286;\" \/><\/p>\n<p>\u4fee\u6539\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">UPDATE \u8868\u540d SET \u5b57\u6bb51=\u503c1, \u5b57\u6bb52=\u503c2,... [WHERE \u6761\u4ef6];<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704293269621.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 453px; --smush-placeholder-aspect-ratio: 453\/73;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704293279298.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 404px; --smush-placeholder-aspect-ratio: 404\/120;\" \/><\/p>\n<p>\u5220\u9664\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">DELETE FROM \u8868\u540d [WHERE \u6761\u4ef6];<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704293884833.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 415px; --smush-placeholder-aspect-ratio: 415\/63;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704293895242.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 346px; --smush-placeholder-aspect-ratio: 346\/103;\" \/><\/p>\n<h1><span class=\"ez-toc-section\" id=\"DQL\"><\/span>DQL<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>Data Query Language\uff0c\u6570\u636e\u67e5\u8be2\u8bed\u8a00<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E5%9F%BA%E6%9C%AC%E6%9F%A5%E8%AF%A2\"><\/span>\u57fa\u672c\u67e5\u8be2<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-mysql\"># \u67e5\u8be2\u6307\u5b9a\u5b57\u6bb5\nSELECT \u5b57\u6bb51, \u5b57\u6bb52, ... FROM \u8868\u540d;\n\n# \u67e5\u8be2\u6240\u6709\u5b57\u6bb5\nSELECT * FROM \u8868\u540d;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704295347387.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 273px; --smush-placeholder-aspect-ratio: 273\/417;\" \/><\/p>\n<p>\u6761\u4ef6\u67e5\u8be2<\/p>\n<pre><code class=\"language-mysql\">SELECT \u5b57\u6bb5\u5217\u8868 FROM \u8868\u540d WHERE \u6761\u4ef6<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704327216754.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 414px; --smush-placeholder-aspect-ratio: 414\/164;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E8%81%9A%E5%90%88%E5%87%BD%E6%95%B0\"><\/span>\u805a\u5408\u51fd\u6570<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u5e38\u7528\u805a\u5408\u51fd\u6570<\/p>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|}\n\\hline\n\u51fd\u6570 &amp; \u63cf\u8ff0 \\\\\n\\hline\nCOUNT &amp; \u7edf\u8ba1\u6570\u91cf \\\\\n\\hline\nMAX &amp; \u6700\u5927\u503c \\\\\n\\hline\nMIN &amp; \u6700\u5c0f\u503c \\\\\n\\hline\nAVG &amp; \u5e73\u5747\u503c \\\\\n\\hline\nSUM &amp; \u6c42\u548c \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<p>\u4f7f\u7528<\/p>\n<pre><code class=\"language-mysql\">SELECT \u805a\u5408\u51fd\u6570(\u5b57\u6bb5\u5217\u8868) FROM \u8868\u540d<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704328313577.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 346px; --smush-placeholder-aspect-ratio: 346\/445;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E5%88%86%E7%BB%84%E6%9F%A5%E8%AF%A2\"><\/span>\u5206\u7ec4\u67e5\u8be2<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-mysql\">SELECT \u5b57\u6bb5\u5217\u8868 FROM \u8868\u540d [WHERE \u6761\u4ef6] GROUP BY \u5206\u7ec4\u5b57\u6bb5 [HAVING \u5206\u7ec4\u540e\u7684\u8fc7\u6ee4\u6761\u4ef6]<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704329377409.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 493px; --smush-placeholder-aspect-ratio: 493\/172;\" \/><\/p>\n<p>\u7edf\u8ba1\u7537\u5973\u6570\u91cf<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704329324409.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 530px; --smush-placeholder-aspect-ratio: 530\/161;\" \/><\/p>\n<p>\u7edf\u8ba1\u7537\u5973\u5404\u81ea\u7684\u5e73\u5747\u5e74\u9f84<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704329470178.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 536px; --smush-placeholder-aspect-ratio: 536\/178;\" \/><\/p>\n<p>\u9996\u5148\u7528 WHERE \u7b5b\u9009\u51fa\u5e74\u9f84\u5927\u4e8e 20 \u7684\uff0c\u518d\u6839\u636e\u57ce\u5e02\u5206\u7ec4\uff0c\u7136\u540e HAVING \u4ece\u5206\u7ec4\u4e2d\u627e COUNT \u8ba1\u6570\u5927\u4e8e 1 \u7684\uff0c\u6700\u540e SELECT \u663e\u793a\u51fa\u5bf9\u5e94\u7684 city \u548c\u6570\u91cf\u3002<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704348771493.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 422px; --smush-placeholder-aspect-ratio: 422\/176;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704348758892.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 803px; --smush-placeholder-aspect-ratio: 803\/357;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E6%8E%92%E5%BA%8F%E6%9F%A5%E8%AF%A2\"><\/span>\u6392\u5e8f\u67e5\u8be2<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-mysql\">SELECT \u5b57\u6bb5\u5217\u8868 FROM \u8868\u540d ORDER BY \u5b57\u6bb51 \u6392\u5e8f\u65b9\u5f0f, \u5b57\u6bb52 \u6392\u5e8f\u65b9\u5f0f, ...<\/code><\/pre>\n<p>ASC \u5347\u5e8f\uff0c\u9ed8\u8ba4\uff1b<br \/>\nDESC \u964d\u5e8f\u3002<\/p>\n<p>\u6839\u636e\u5e74\u9f84\u6392\u5e8f\uff08\u5347\u5e8f\uff09<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704350892337.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 401px; --smush-placeholder-aspect-ratio: 401\/411;\" \/><\/p>\n<p>\u6309\u5e74\u9f84\u964d\u5e8f\u6392\u5e8f\uff0c\u5e74\u9f84\u76f8\u540c\u65f6\u4f1a\u91c7\u7528\u7b2c\u4e8c\u4e2a\u5b57\u6bb5\u8eab\u9ad8\u6392\u5e8f\uff08\u4e0d\u6307\u5b9a\u9ed8\u8ba4\u5347\u5e8f\uff09<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704351185362.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 481px; --smush-placeholder-aspect-ratio: 481\/203;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E5%88%86%E9%A1%B5%E6%9F%A5%E8%AF%A2\"><\/span>\u5206\u9875\u67e5\u8be2<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-mysql\">SELECT \u5b57\u6bb5\u5217\u8868 FROM \u8868\u540d LIMIT \u8d77\u59cb\u7d22\u5f15, \u67e5\u8be2\u8bb0\u5f55\u6570;<\/code><\/pre>\n<p>\u8d77\u59cb\u7d22\u5f15\u4ece 0 \u5f00\u59cb\uff0c\u548c\u5927\u591a\u6570\u7f16\u7a0b\u8bed\u8a00\u91cc\u7684\u6570\u7ec4\u7d22\u5f15\u4e00\u6837\u3002<br \/>\n\u4e0b\u9762\u793a\u4f8b\u662f\u67e5\u8be2\u4ece\u7d22\u5f15 3 \u5f00\u59cb\uff08\u7b2c 4 \u4e2a\uff09\u7684 3 \u4e2a\u6570\u636e<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704352173013.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 964px; --smush-placeholder-aspect-ratio: 964\/226;\" \/><\/p>\n<h1><span class=\"ez-toc-section\" id=\"DCL\"><\/span>DCL<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>Data Control Language\uff0c\u6570\u636e\u63a7\u5236\u8bed\u8a00<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E7%94%A8%E6%88%B7%E7%AE%A1%E7%90%86\"><\/span>\u7528\u6237\u7ba1\u7406<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u67e5\u8be2\u7528\u6237<\/p>\n<pre><code class=\"language-mysql\">USE mysql;\nSELECT * FROM user;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704639228190.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 545px; --smush-placeholder-aspect-ratio: 545\/229;\" \/><\/p>\n<p>\u521b\u5efa\u7528\u6237<\/p>\n<pre><code class=\"language-mysql\">CREATE USER &quot;\u7528\u6237\u540d&quot;@&quot;\u4e3b\u673a\u540d&quot; IDENTIFIED BY &quot;\u5bc6\u7801&quot;;<\/code><\/pre>\n<p>\u5176\u4e2d localhost \u6307\u672c\u5730\u4e3b\u673a\uff0c\u5982\u679c\u8981\u4efb\u610f\u4e3b\u673a\u90fd\u53ef\u8bbf\u95ee\uff0c\u53ef\u4ee5\u4f7f\u7528 <strong>%<\/strong>\u3002<\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704639499788.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 570px; --smush-placeholder-aspect-ratio: 570\/55;\" \/><\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704639511903.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 455px; --smush-placeholder-aspect-ratio: 455\/205;\" \/><\/p>\n<p>\u4fee\u6539\u7528\u6237\u5bc6\u7801<\/p>\n<pre><code class=\"language-mysql\">ALTER USER &quot;\u7528\u6237\u540d&quot;@&quot;\u4e3b\u673a\u540d&quot; IDENTIFIED WITH mysql_native_password BY &quot;\u65b0\u5bc6\u7801&quot;;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704639970857.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 820px; --smush-placeholder-aspect-ratio: 820\/50;\" \/><\/p>\n<p>\u5220\u9664\u7528\u6237<\/p>\n<pre><code class=\"language-mysql\">DROP USER &quot;\u7528\u6237\u540d&quot;@&quot;\u4e3b\u673a\u540d&quot;;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704640074782.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 400px; --smush-placeholder-aspect-ratio: 400\/55;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E6%9D%83%E9%99%90%E6%8E%A7%E5%88%B6\"><\/span>\u6743\u9650\u63a7\u5236<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u5e38\u7528\u6743\u9650<\/p>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|}\n\\hline\n\u6743\u9650 &amp; \u63cf\u8ff0 \\\\\n\\hline\nALL\/ALL\\ PRIVILEGES &amp; \u6240\u6709\u6743\u9650 \\\\\n\\hline\nSELECT &amp; \u67e5\u8be2\u6570\u636e \\\\\n\\hline\nINSERT &amp; \u63d2\u5165\u6570\u636e \\\\\n\\hline\nUPDATE &amp; \u4fee\u6539\u6570\u636e \\\\\n\\hline\nDELETE &amp; \u5220\u9664\u6570\u636e \\\\\n\\hline\nALTER &amp; \u4fee\u6539\u8868 \\\\\n\\hline\nDROP &amp; \u5220\u9664\u6570\u636e\u5e93\/\u8868\/\u8bd5\u56fe \\\\\n\\hline\nCREATE &amp; \u521b\u5efa\u6570\u636e\u5e93\/\u8868 \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<p>\u67e5\u8be2\u6743\u9650<\/p>\n<pre><code class=\"language-mysql\">SHOW GRANTS FOR &quot;\u7528\u6237\u540d&quot;@&quot;\u4e3b\u673a\u540d&quot;;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704641251120.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 340px; --smush-placeholder-aspect-ratio: 340\/148;\" \/><\/p>\n<p>\u6388\u4e88\u6743\u9650<\/p>\n<pre><code class=\"language-mysql\">GRANT \u6743\u9650\u5217\u8868 ON \u6570\u636e\u5e93\u540d.\u8868\u540d TO &quot;\u7528\u6237\u540d&quot;@&quot;\u4e3b\u673a\u540d&quot;\uff1b<\/code><\/pre>\n<p>\u64a4\u9500\u6743\u9650<\/p>\n<pre><code class=\"language-mysql\">REVOKE \u6743\u9650\u5217\u8868 ON \u6570\u636e\u5e93\u540d.\u8868\u540d FROM &quot;\u7528\u6237\u540d&quot;@&quot;\u4e3b\u673a\u540d&quot;;<\/code><\/pre>\n<h1><span class=\"ez-toc-section\" id=\"%E5%B8%B8%E7%94%A8%E5%86%85%E7%BD%AE%E5%87%BD%E6%95%B0\"><\/span>\u5e38\u7528\u5185\u7f6e\u51fd\u6570<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<h2><span class=\"ez-toc-section\" id=\"%E5%AD%97%E7%AC%A6%E4%B8%B2%E5%87%BD%E6%95%B0\"><\/span>\u5b57\u7b26\u4e32\u51fd\u6570<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|}\n\\hline\n\u51fd\u6570 &amp; \u63cf\u8ff0 \\\\\n\\hline\nCONCAT(S1, S2,...,Sn) &amp; \u5b57\u7b26\u4e32\u62fc\u63a5 \\\\\n\\hline\nLOWER(S) &amp; \u5c06\u5b57\u7b26\u4e32\u8f6c\u4e3a\u5c0f\u5199 \\\\\n\\hline\nUPPER(S) &amp; \u5c06\u5b57\u7b26\u4e32\u8f6c\u4e3a\u5927\u5199 \\\\\n\\hline\nLPAD(S, n, pad) &amp; \u5b57\u7b26\u4e32\u5de6\u4fa7\u586b\u5145\uff0c\u7528 pad \u586b\u5145 S \u7684\u5de6\u4fa7\uff0c\u4f7f\u603b\u957f\u5ea6\u8fbe\u5230 n \\\\\n\\hline\nRPAD(S, n, pad) &amp; \u5b57\u7b26\u4e32\u53c8\u586b\u5145\uff0c\u7528 pad \u586b\u5145 S \u7684\u53f3\u4fa7\uff0c\u4f7f\u603b\u957f\u5ea6\u8fbe\u5230 n \\\\\n\\hline\nTRIM(S) &amp; \u53bb\u6389\u5b57\u7b26\u4e32\u5934\u5c3e\u7684\u7a7a\u683c \\\\\n\\hline\nSUBSTRING(S, start, len) &amp; \u8fd4\u56de\u5b57\u7b26\u4e32 S \u4ece start \u5f00\u59cb\u7684 len \u4e2a\u957f\u5ea6\u7684\u5b57\u7b26\u4e32 \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704789425381.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 415px; --smush-placeholder-aspect-ratio: 415\/153;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704790634225.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 318px; --smush-placeholder-aspect-ratio: 318\/146;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704790653153.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 323px; --smush-placeholder-aspect-ratio: 323\/148;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704790717543.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 364px; --smush-placeholder-aspect-ratio: 364\/154;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704790897430.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 437px; --smush-placeholder-aspect-ratio: 437\/300;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704790734169.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 366px; --smush-placeholder-aspect-ratio: 366\/148;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704790766113.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 364px; --smush-placeholder-aspect-ratio: 364\/154;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E6%95%B0%E5%80%BC%E5%87%BD%E6%95%B0\"><\/span>\u6570\u503c\u51fd\u6570<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|}\n\\hline\n\u51fd\u6570 &amp; \u63cf\u8ff0 \\\\\n\\hline\nCEIL(x) &amp; \u5411\u4e0a\u53d6\u6574 \\\\\n\\hline\nFLOOR(x) &amp; \u5411\u4e0b\u53d6\u6574 \\\\\n\\hline\nMOD(x, y) &amp; \u8ba1\u7b97 x \/ y \u7684\u6a21 \\\\\n\\hline\nRAND() &amp; \u751f\u6210 0-1 \u4e4b\u95f4\u7684\u968f\u673a\u6570 \\\\\n\\hline\nROUND(x, y) &amp; \u6c42 x \u7684\u56db\u820d\u4e94\u5165\u503c\uff0c\u4fdd\u7559 y \u4f4d\u5c0f\u6570 \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704791159826.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 232px; --smush-placeholder-aspect-ratio: 232\/145;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704791183102.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 244px; --smush-placeholder-aspect-ratio: 244\/150;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704791206188.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 235px; --smush-placeholder-aspect-ratio: 235\/156;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704791236339.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 232px; --smush-placeholder-aspect-ratio: 232\/166;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704791278193.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 289px; --smush-placeholder-aspect-ratio: 289\/143;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E6%97%A5%E6%9C%9F%E5%87%BD%E6%95%B0\"><\/span>\u65e5\u671f\u51fd\u6570<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|}\n\\hline\nCURDATA() &amp; \u8fd4\u56de\u5f53\u524d\u65e5\u671f \\\\\n\\hline\nCURTIME() &amp; \u8fd4\u56de\u5f53\u524d\u65f6\u95f4 \\\\\n\\hline\nNOW() &amp; \u8fd4\u56de\u5f53\u524d\u65e5\u671f\u548c\u65f6\u95f4 \\\\\n\\hline\nYEAR(date) &amp; \u83b7\u53d6 date \u7684\u5e74\u4efd \\\\\n\\hline\nMONTH(date) &amp; \u83b7\u53d6 date \u7684\u6708\u4efd \\\\\n\\hline\nDAY(date) &amp; \u83b7\u53d6 date \u7684\u65e5\u671f \\\\\n\\hline\nDATE\\_ADD(date, INTERVAL expr type) &amp; \u8fd4\u56de date \u52a0\u4e0a\u65f6\u95f4\u95f4\u9694 expr \u540e\u7684\u65f6\u95f4\u503c \\\\\n\\hline\nDATEDIFF(date1, date2) &amp; \u8fd4\u56de date1 \u548c date2 \u4e4b\u95f4\u7684\u5929\u6570\u5dee\u503c \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704798289863.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 242px; --smush-placeholder-aspect-ratio: 242\/146;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704798315730.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 237px; --smush-placeholder-aspect-ratio: 237\/149;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704798342060.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 227px; --smush-placeholder-aspect-ratio: 227\/151;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704798390673.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 283px; --smush-placeholder-aspect-ratio: 283\/301;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704798430484.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 263px; --smush-placeholder-aspect-ratio: 263\/159;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704798446578.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 244px; --smush-placeholder-aspect-ratio: 244\/153;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704798606846.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 453px; --smush-placeholder-aspect-ratio: 453\/913;\" \/><\/p>\n<p>\u4e0d\u5f97\u4e0d\u611f\u6168\u4ece\u5c0f\u5b66\u5f00\u59cb\u8bfb\u4e66\u81f3\u4eca\u5df2\u7ecf\u8fc7\u53bb 5974 \u5929\u4e86<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704798733137.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 391px; --smush-placeholder-aspect-ratio: 391\/154;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E6%B5%81%E7%A8%8B%E5%87%BD%E6%95%B0\"><\/span>\u6d41\u7a0b\u51fd\u6570<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|}\n\\hline\n\u65e5\u671f &amp; \u51fd\u6570 \\\\\n\\hline\nIF(value, t, f) &amp; \u5982\u679c value \u4e3a TRUE\uff0c\u5219\u8fd4\u56de t\uff0c\u5426\u4e3a\u8fd4\u56de f \\\\\n\\hline\nIFNULL(value1, value2) &amp; \u5982\u679c value1 \u4e0d\u4e3a\u7a7a\u5219\u8fd4\u56de value1\uff0c\u5426\u5219\u8fd4\u56de value2 \\\\\n\\hline\nCASE\\ WHEN\\ [val1]\\ THEN\\ [res1]\\ ...\\ ELSE\\ [default]\\ END &amp; \u5982\u679c val1 \u4e3a TRUE\uff0c\u8fd4\u56deres1,...\uff0c\u5426\u5219\u8fd4\u56de default \u9ed8\u8ba4\u503c \\\\\n\\hline\nCASE\\ expr\\ WHEN\\ [val1]\\ THEN\\ [res1]\\ ...\\ ELSE\\ [default]\\ END &amp; \u5982\u679c expr \u7b49\u4e8eval1\uff0c\u8fd4\u56de res1,...,\u5426\u5219\u8fd4\u56dedefault\u9ed8\u8ba4\u503c \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704801120684.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 303px; --smush-placeholder-aspect-ratio: 303\/207;\" \/><\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704800261562.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 579px; --smush-placeholder-aspect-ratio: 579\/462;\" \/><\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704800316531.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 416px; --smush-placeholder-aspect-ratio: 416\/284;\" \/><\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704800891442.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 404px; --smush-placeholder-aspect-ratio: 404\/541;\" \/><\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704801506853.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 338px; --smush-placeholder-aspect-ratio: 338\/590;\" \/><\/p>\n<h1><span class=\"ez-toc-section\" id=\"%E7%BA%A6%E6%9D%9F\"><\/span>\u7ea6\u675f<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>\u5e38\u7528\u7ea6\u675f<\/p>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|l|}\n\\hline\n\u7ea6\u675f &amp; \u63cf\u8ff0 &amp; \u5173\u952e\u5b57 \\\\\n\\hline\n\u975e\u7a7a\u7ea6\u675f &amp; \u9650\u5236\u5b57\u6bb5\u6570\u636e\u4e0d\u80fd\u4e3a NULL &amp; NOT NULL \\\\\n\\hline\n\u552f\u4e00\u7ea6\u675f &amp; \u5b57\u6bb5\u7684\u6240\u6709\u6570\u636e\u90fd\u662f\u552f\u4e00\u7684\uff0c\u4e0d\u80fd\u91cd\u590d &amp; UNIQUE \\\\\n\\hline\n\u4e3b\u952e\u7ea6\u675f &amp; \u4e3b\u952e\u662f\u4e00\u884c\u6570\u636e\u7684\u552f\u4e00\u6807\u8bc6\uff0c\u8981\u6c42\u975e\u7a7a\u4e14\u552f\u4e00 &amp; PRIMARY\\ KEY \\\\\n\\hline\n\u9ed8\u8ba4\u7ea6\u675f &amp; \u672a\u6307\u5b9a\u5b57\u6bb5\u7684\u503c\u91c7\u7528\u9ed8\u8ba4\u503c &amp; DEFAULT \\\\\n\\hline\n\u68c0\u67e5\u7ea6\u675f\uff088.0.16 \u4ee5\u540e\uff09&amp; \u4fdd\u8bc1\u5b57\u6bb5\u503c\u6ee1\u8db3\u67d0\u6761\u4ef6 &amp; CHECK \\\\\n\\hline\n\u5916\u952e\u7ea6\u675f &amp; \u8ba9\u4e24\u5f20\u8868\u7684\u6570\u636e\u5efa\u7acb\u8fde\u63a5\uff0c\u4fdd\u8bc1\u6570\u636e\u7684\u4e00\u81f4\u6027\u548c\u5b8c\u6574\u6027 &amp; FOREIGN\\ KEY \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<h2><span class=\"ez-toc-section\" id=\"%E4%B8%80%E8%88%AC%E7%BA%A6%E6%9D%9F%E7%A4%BA%E4%BE%8B\"><\/span>\u4e00\u822c\u7ea6\u675f\u793a\u4f8b<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u521b\u5efa\u4e00\u4e2a\u6ee1\u8db3\u4e0b\u9762\u7ed3\u6784\u8981\u6c42\u7684\u8868<\/p>\n<ul>\n<li>id\uff1a\u552f\u4e00\u6807\u8bc6\uff0c\u5b57\u6bb5\u7c7b\u578b INT\uff0c\u7ea6\u675f\u6761\u4ef6\uff1a\u4e3b\u952e\u4e14\u81ea\u52a8\u589e\u957f<\/li>\n<li>name\uff1a\u59d3\u540d\uff0c\u5b57\u6bb5\u7c7b\u578b VARCHAR(10)\uff0c\u7ea6\u675f\u6761\u4ef6\uff1a\u4e0d\u4e3a\u7a7a\u4e14\u552f\u4e00<\/li>\n<li>age\uff1a\u5e74\u9f84\uff0c\u5b57\u6bb5\u7c7b\u578b TINYINT\uff0c\u7ea6\u675f\u6761\u4ef6\uff1a\u4e0d\u5c0f\u4e8e 0 \u4e14\u4e0d\u8d85\u8fc7 200<\/li>\n<li>status\uff1a\u8eab\u4f53\u5065\u5eb7\u72b6\u6001\uff0c\u5b57\u6bb5\u7c7b\u578b CHAR(1)\uff0c\u7ea6\u675f\u6761\u4ef6\uff1a\u4e0d\u6307\u5b9a\u9ed8\u8ba4\u4e3a 1<\/li>\n<li>gender\uff1a\u6027\u522b\uff0c\u5b57\u6bb5\u7c7b\u578b CHAR(1)\uff0c\u7ea6\u675f\u6761\u4ef6\uff1a\u503c\u4e3a\u7537\u6216\u5973<\/li>\n<\/ul>\n<p>\u521b\u5efa\u8868<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE new_user (\n    id INT PRIMARY KEY AUTO_INCREMENT COMMENT &quot;\u552f\u4e00\u6807\u8bc6&quot;,\n    name VARCHAR(10) NOT NULL UNIQUE COMMENT &quot;\u59d3\u540d&quot;,\n    age TINYINT CHECK ( age &gt;=0 &amp;&amp; age &lt;= 200 ),\n    status CHAR(1) DEFAULT &quot;1&quot; COMMENT &quot;\u5065\u5eb7\u72b6\u6001&quot;,\n    gender CHAR(1) CHECK ( gender = &quot;\u7537&quot; || gender = &quot;\u5973&quot; ) COMMENT &quot;\u6027\u522b&quot;\n) COMMENT &quot;\u7528\u6237\u8868&quot;;<\/code><\/pre>\n<p>\u63d2\u5165\u6570\u636e\u9a8c\u8bc1\uff1a<br \/>\nID \u53ef\u4ee5\u4e0d\u7528\u586b\u5199\uff0c\u63d0\u4ea4\u81ea\u52a8\u4ece 1 \u5f00\u59cb\u751f\u6210<br \/>\n\u5f53 name \u91cd\u590d\u65f6\uff0c\u63d0\u4ea4\u62a5\u9519<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704808327399.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 752px; --smush-placeholder-aspect-ratio: 752\/441;\" \/><br \/>\n\u5f53\u5e74\u9f84\u8d85\u51fa\u7ea6\u675f\u8303\u56f4\uff0c\u63d0\u4ea4\u62a5\u9519<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704808376359.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 839px; --smush-placeholder-aspect-ratio: 839\/442;\" \/><br \/>\nstatus \u4e0d\u586b\u5199\uff0c\u63d0\u4ea4\u9ed8\u8ba4\u4e3a 1<br \/>\n\u5f53\u6027\u522b\u586b\u5199\u975e\u7537\u975e\u5973\u65f6\uff0c\u63d0\u4ea4\u62a5\u9519<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704808475416.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 697px; --smush-placeholder-aspect-ratio: 697\/460;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E5%A4%96%E9%94%AE%E7%BA%A6%E6%9D%9F%E7%A4%BA%E4%BE%8B\"><\/span>\u5916\u952e\u7ea6\u675f\u793a\u4f8b<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3><span class=\"ez-toc-section\" id=\"%E5%88%9B%E5%BB%BA%E8%A1%A8%E6%97%B6%E6%B7%BB%E5%8A%A0%E5%A4%96%E9%94%AE\"><\/span>\u521b\u5efa\u8868\u65f6\u6dfb\u52a0\u5916\u952e<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<pre><code class=\"language-mysql\">CREATE TABLE \u8868\u540d (\n    \u5b57\u6bb5\u540d \u7c7b\u578b,\n    ...\n    [CONSTRAINT] [\u5916\u952e\u540d\u79f0] FOREIGN KEY (\u5916\u952e\u5b57\u6bb5\u540d) REFERENCES \u4e3b\u8868(\u4e3b\u8868\u5217\u540d)\n);<\/code><\/pre>\n<p>\u8fd9\u91cc\u5148\u521b\u5efa\u4e00\u4e2a\u7236\u8868<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE classes (\n                         id TINYINT COMMENT &quot;\u73ed\u7ea7\u6807\u8bc6&quot; PRIMARY KEY , # \u4e3b\u952e\u7ea6\u675f\n                         name CHAR(2) COMMENT &quot;\u73ed\u540d&quot;\n) COMMENT &quot;\u73ed\u7ea7\u8868&quot;;<\/code><\/pre>\n<p>\u7236\u8868\u63d2\u5165\u5185\u5bb9<\/p>\n<pre><code class=\"language-mysqll\">INSERT INTO classes VALUES\n                        (1, &quot;1\u73ed&quot;),\n                        (2, &quot;2\u73ed&quot;),\n                        (3, &quot;3\u73ed&quot;);<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704861554033.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 243px; --smush-placeholder-aspect-ratio: 243\/152;\" \/><\/p>\n<p>\u521b\u5efa\u4e00\u4e2a\u5173\u8054\u5230\u7236\u8868\u7684\u5b50\u8868<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE students (\n    name VARCHAR(10) COMMENT &quot;\u59d3\u540d&quot;,\n    age TINYINT COMMENT &quot;\u5e74\u9f84&quot;,\n    class_id TINYINT COMMENT &quot;\u73ed\u7ea7\u6807\u8bc6&quot;,\n    CONSTRAINT fk_students_classes_id FOREIGN Key (class_id) REFERENCES classes(id)\n) COMMENT &quot;\u5b66\u751f\u8868&quot;;<\/code><\/pre>\n<p>\u5b50\u8868\u63d2\u5165\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">INSERT INTO students VALUES\n                         (&quot;\u5c0f\u5f3a&quot;, 19, 1),\n                         (&quot;\u5c0f\u7ea2&quot;, 20, 2),\n                         (&quot;\u5c0f\u5f20&quot;, 20, 3),\n                         (&quot;\u5c0f\u519b&quot;, 18, 2);<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704862459897.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 393px; --smush-placeholder-aspect-ratio: 393\/176;\" \/><\/p>\n<p>\u5982\u679c\u5c1d\u8bd5\u5220\u9664\u7236\u8868\u4e2d\u7684\u884c\u6570\u636e\u5c31\u4f1a\u63d0\u793a\u4e0d\u80fd\u64cd\u4f5c<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704862733278.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 1111px; --smush-placeholder-aspect-ratio: 1111\/86;\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E7%8E%B0%E6%9C%89%E8%A1%A8%E6%B7%BB%E5%8A%A0%E5%A4%96%E9%94%AE\"><\/span>\u73b0\u6709\u8868\u6dfb\u52a0\u5916\u952e<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<pre><code class=\"language-mysql\">ALTER TABLE \u8868\u540d ADD CONSTRAINT \u5916\u952e\u540d\u79f0 FOREIGN KEY \uff08\u5916\u952e\u5b57\u6bb5\u540d) REFERENCES \u4e3b\u8868(\u4e3b\u8868\u5217\u540d);<\/code><\/pre>\n<p>\u5047\u5982\u662f\u5df2\u7ecf\u521b\u5efa\u4e86\u4e00\u5f20\u8868<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE stu (\n    name VARCHAR(10) COMMENT &quot;\u540d\u5b57&quot;,\n    class_id TINYINT COMMENT &quot;\u73ed\u7ea7\u6807\u8bc6&quot;\n) COMMENT &quot;\u5b66\u751f\u8868&quot;;<\/code><\/pre>\n<p>\u5b50\u8868\u63d2\u5165\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">INSERT INTO stu VALUES\n                    (&quot;\u5c0f\u660e&quot;, 1),\n                    (&quot;\u5c0f\u7ea2&quot;, 2),\n                    (&quot;\u5c0f\u5f3a&quot;, 3);<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704866400139.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 281px; --smush-placeholder-aspect-ratio: 281\/133;\" \/><\/p>\n<p>\u540e\u671f\u6dfb\u52a0\u5916\u952e\u7ea6\u675f<\/p>\n<pre><code class=\"language-mysql\">ALTER TABLE stu ADD CONSTRAINT fk_stu_class_id FOREIGN KEY (class_id) REFERENCES classes(id);<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704865943189.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 921px; --smush-placeholder-aspect-ratio: 921\/75;\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E5%88%A0%E9%99%A4%E5%A4%96%E9%94%AE\"><\/span>\u5220\u9664\u5916\u952e<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<pre><code class=\"language-mysql\">ALTER TABLE \u8868\u540d DROP FOREIGN KEY \u5916\u952e\u540d\u79f0;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704867464785.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 633px; --smush-placeholder-aspect-ratio: 633\/79;\" \/><\/p>\n<p>\u5916\u952e\u540d\u79f0\u53ef\u4ee5\u901a\u8fc7\u67e5\u770b\u8868\u7684\u521b\u5efa\u8bed\u53e5\u770b\u5230<\/p>\n<pre><code class=\"language-mysql\">SHOW CREATE TABLE \u8868\u540d<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704867369456.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 826px; --smush-placeholder-aspect-ratio: 826\/495;\" \/><\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704867392215.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 798px; --smush-placeholder-aspect-ratio: 798\/390;\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E5%A4%96%E9%94%AE%E7%BA%A6%E6%9D%9F%E8%A1%8C%E4%B8%BA\"><\/span>\u5916\u952e\u7ea6\u675f\u884c\u4e3a<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|}\n\\hline\n\u884c\u4e3a &amp; \u63cf\u8ff0 \\\\\n\\hline\nNO ACTION &amp; \u7236\u8868\u4e2d\u5220\u9664\u6216\u66f4\u65b0\u8bb0\u5f55\u65f6\uff0c\u9996\u5148\u68c0\u67e5\u8be5\u8bb0\u5f55\u662f\u5426\u6709\u5bf9\u5e94\u5916\u952e\uff0c\u6709\u5219\u4e0d\u5141\u8bb8\u5220\u9664\u6216\u66f4\u65b0 \\\\\n\\hline\nRESTRICT &amp; \u4f5c\u7528\u540c\u4e0a\uff0c\u53ea\u662f RESTRICT \u662f\u5728\u64cd\u4f5c\u53d1\u751f\u524d\u5c31\u8d77\u4f5c\u7528\uff0c\u800c NO ACTION \u662f\u5728\u5220\u9664\u6216\u66f4\u65b0\u64cd\u4f5c\u89e6\u53d1\u65f6\u624d\u8d77\u4f5c\u7528\uff0c\u53ef\u4ee5\u770b\u505a\u5ef6\u8fdf\u68c0\u67e5\u3002\u9ed8\u8ba4\u884c\u4e3a\u3002 \\\\\n\\hline\nCASCADE &amp; \u7236\u8868\u4e2d\u5220\u9664\u6216\u66f4\u65b0\u8bb0\u5f55\u65f6\uff0c\u9996\u5148\u68c0\u67e5\u8bb0\u5f55\u662f\u5426\u6709\u5bf9\u5e94\u5916\u952e\uff0c\u5982\u679c\u6709\uff0c\u5219\u4e5f\u5220\u9664\u6216\u66f4\u65b0\u5916\u952e\u5728\u5b50\u8868\u4e2d\u7684\u8bb0\u5f55 \\\\\n\\hline\nSET NULL &amp; \u7236\u8868\u4e2d\u5220\u9664\u8bb0\u5f55\u65f6\uff0c\u9996\u5148\u68c0\u67e5\u8bb0\u5f55\u662f\u5426\u6709\u5bf9\u5e94\u5916\u952e\uff0c\u6709\u5219\u8bbe\u7f6e\u5b50\u8868\u4e2d\u8be5\u5916\u952e\u4e3a NULL\uff08\u9700\u8981\u6539\u5916\u952e\u5141\u8bb8\u53d6 NULL) \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<p>\u6307\u5b9a\u5916\u952e\u7ea6\u675f\u884c\u4e3a<\/p>\n<pre><code class=\"language-mysql\">```mysql\nCREATE TABLE \u8868\u540d (\n    \u5b57\u6bb5\u540d \u7c7b\u578b,\n    ...\n    [CONSTRAINT] [\u5916\u952e\u540d\u79f0] FOREIGN KEY (\u5916\u952e\u5b57\u6bb5\u540d) REFERENCES \u4e3b\u8868(\u4e3b\u8868\u5217\u540d) ON UPDATE \u66f4\u65b0\u65f6\u884c\u4e3a ON DELETE \u5220\u9664\u65f6\u884c\u4e3a;\n);<\/code><\/pre>\n<pre><code>\n```mysql\nALTER TABLE \u8868\u540d ADD CONSTRAINT \u5916\u952e\u540d\u79f0 FOREIGN KEY (\u5916\u952e\u5b57\u6bb5) REFERENCES \u4e3b\u8868\u540d(\u4e3b\u8868\u5b57\u6bb5\u540d) ON UPDATE \u66f4\u65b0\u65f6\u884c\u4e3a ON DELETE \u5220\u9664\u65f6\u884c\u4e3a;<\/code><\/pre>\n<p>\u6ce8\uff1a\u5982\u679c\u5df2\u6709\u5916\u952e\u7ea6\u675f\uff0c\u8981\u4fee\u6539\u884c\u4e3a\uff0c\u9700\u8981\u5148\u5220\u9664\u539f\u6709\u7684\u5916\u952e\u7ea6\u675f\uff0c\u7136\u540e\u91cd\u65b0\u5efa\u7acb\u5916\u952e\u65f6\u6307\u5b9a\u884c\u4e3a\u3002<\/p>\n<p>\u793a\u4f8b\uff1a<br \/>\n\u521b\u5efa\u4e00\u4e2a\u7236\u8868<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE classes (\n                         id TINYINT COMMENT \"\u73ed\u7ea7\u6807\u8bc6\" PRIMARY KEY , # \u4e3b\u952e\u7ea6\u675f\n                         name CHAR(2) COMMENT \"\u73ed\u540d\"\n) COMMENT \"\u73ed\u7ea7\u8868\";<\/code><\/pre>\n<p>\u7236\u8868\u63d2\u5165\u5185\u5bb9<\/p>\n<pre><code class=\"language-mysqll\">INSERT INTO classes VALUES\n                        (1, \"1\u73ed\"),\n                        (2, \"2\u73ed\"),\n                        (3, \"3\u73ed\");<\/code><\/pre>\n<p>\u521b\u5efa\u4e00\u4e2a\u5b50\u8868\uff0c\u5916\u952e\u7ea6\u675f\u884c\u4e3a\u90fd\u662f CASCADE<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE students (\n                          name VARCHAR(10) COMMENT \"\u59d3\u540d\",\n                          age TINYINT COMMENT \"\u5e74\u9f84\",\n                          class_id TINYINT COMMENT \"\u73ed\u7ea7\u6807\u8bc6\",\n                          CONSTRAINT fk_students_classes_id FOREIGN Key (class_id) REFERENCES classes(id) ON UPDATE CASCADE ON DELETE CASCADE\n) COMMENT \"\u5b66\u751f\u8868\";<\/code><\/pre>\n<p>\u5b50\u8868\u63d2\u5165\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">INSERT INTO students VALUES\n                         (\"\u5c0f\u5f3a\", 19, 1),\n                         (\"\u5c0f\u7ea2\", 20, 2),\n                         (\"\u5c0f\u5f20\", 20, 3),\n                         (\"\u5c0f\u519b\", 18, 2);<\/code><\/pre>\n<p>\u4fee\u6539\u7236\u8868<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704884093785.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 229px; --smush-placeholder-aspect-ratio: 229\/139;\" \/><br \/>\n\u5b50\u8868\u540c\u6b65\u66f4\u65b0\u4e86 id<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704884112771.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 393px; --smush-placeholder-aspect-ratio: 393\/174;\" \/><\/p>\n<p>\u5220\u9664\u7236\u8868\u6570\u636e<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704884170892.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 226px; --smush-placeholder-aspect-ratio: 226\/107;\" \/><br \/>\n\u5b50\u8868\u540c\u6b65\u5220\u9664\u4e86<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704884188309.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 376px; --smush-placeholder-aspect-ratio: 376\/137;\" \/><\/p>\n<p>\u5982\u679c\u8bbe\u7f6e\u7684\u5916\u952e\u884c\u4e3a\u662f SET NULL\uff0c\u5219\u4fee\u6539\u7236\u8868\u6216\u5220\u9664\u5b50\u8868\u7684\u67d0\u884c\u5143\u7d20\u540e\uff0c\u5b50\u8868\u4e2d\u5bf9\u5e94\u7684\u5916\u952e\u4f1a\u6539\u4e3a NULL\u3002<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704884647777.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 386px; --smush-placeholder-aspect-ratio: 386\/153;\" \/><\/p>\n<h1><span class=\"ez-toc-section\" id=\"%E5%A4%9A%E8%A1%A8%E6%9F%A5%E8%AF%A2\"><\/span>\u591a\u8868\u67e5\u8be2<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<h2><span class=\"ez-toc-section\" id=\"%E5%85%B3%E7%B3%BB\"><\/span>\u5173\u7cfb<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3><span class=\"ez-toc-section\" id=\"%E4%B8%80%E5%AF%B9%E4%B8%80\"><\/span>\u4e00\u5bf9\u4e00<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u6bd4\u5982\u5b66\u751f\u53ef\u4ee5\u6709\u5b66\u751f\u4fe1\u606f\uff0c\u4e5f\u6709\u793e\u4f1a\u4fe1\u606f\uff0c\u5206\u522b\u5efa\u7acb\u4e00\u5f20\u8868\uff0c\u53ef\u4ee5\u901a\u8fc7\u8eab\u4efd\u8bc1\u53f7\u5efa\u7acb\u5916\u952e\u5173\u8054\u8d77\u6765<br \/>\n\u521b\u5efa\u4e00\u5f20\u5b66\u751f\u4fe1\u606f\u8868<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE student (\n    id CHAR(1) COMMENT \"\u8eab\u4efd\u8bc1\u53f7\",\n    name VARCHAR(10) COMMENT \"\u59d3\u540d\",\n    name_of_school VARCHAR(36) COMMENT \"\u5b66\u6821\u540d\"\n) COMMENT \"\u5b66\u751f\u4fe1\u606f\";<\/code><\/pre>\n<p>\u63d2\u5165\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">INSERT INTO student VALUES\n                        (\"1\", \"\u5c0f\u5f3a\", \"A school\"),\n                        (\"2\", \"\u5c0f\u7ea2\", \"B school\"),\n                        (\"3\", \"\u5c0f\u5f20\", \"C school\");<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704892509119.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 428px; --smush-placeholder-aspect-ratio: 428\/152;\" \/><\/p>\n<p>\u521b\u5efa\u4e00\u5f20\u793e\u4f1a\u4fe1\u606f\u8868<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE person (\n    id CHAR(1) COMMENT \"\u8eab\u4efd\u8bc1\u53f7\" PRIMARY KEY,\n    name VARCHAR(10) COMMENT \"\u59d3\u540d\",\n    age TINYINT COMMENT \"\u5e74\u9f84\",\n    address VARCHAR(128) COMMENT \"\u5730\u5740\"\n) COMMENT \"\u793e\u4f1a\u4fe1\u606f\";<\/code><\/pre>\n<p>\u63d2\u5165\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">INSERT INTO person VALUES\n                        (\"1\", \"\u5c0f\u5f3a\", 20, \"AAA\"),\n                        (\"2\", \"\u5c0f\u7ea2\", 19, \"BBB\"),\n                        (\"3\", \"\u5c0f\u5f20\", 20, \"CCC\");<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704892524017.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 458px; --smush-placeholder-aspect-ratio: 458\/139;\" \/><\/p>\n<p>\u5efa\u7acb\u5916\u952e<\/p>\n<pre><code class=\"language-mysql\">ALTER TABLE student\n    ADD CONSTRAINT fk_student_person_id\n    FOREIGN KEY (id)\n    REFERENCES person (id);<\/code><\/pre>\n<p>\u67e5\u8be2<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704893848744.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 613px; --smush-placeholder-aspect-ratio: 613\/162;\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E4%B8%80%E5%AF%B9%E5%A4%9A\"><\/span>\u4e00\u5bf9\u591a<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u4e00\u4e2a\u5b66\u751f\u53ea\u5c5e\u4e8e\u4e00\u4e2a\u73ed\uff0c\u4e00\u4e2a\u73ed\u91cc\u6709\u591a\u4e2a\u5b66\u751f\u3002<br \/>\n\u521b\u5efa\u4e00\u4e2a\u5b66\u751f\u8868<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE student_class (\n    name CHAR(2) COMMENT \"\u540d\u5b57\",\n    class_id CHAR(1) COMMENT \"\u6240\u5c5e\u73ed\u7ea7\u4ee3\u53f7\"\n) COMMENT \"\u5b66\u751f-\u73ed\u7ea7\u8868\";<\/code><\/pre>\n<p>\u63d2\u5165\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">INSERT INTO student_class VALUES \n                              (\"\u5c0f\u5f3a\", \"1\"),\n                              (\"\u5c0f\u5f20\", \"2\"),\n                              (\"\u5c0f\u7ea2\", \"3\"),\n                              (\"\u5c0f\u521a\", NULL);<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704895900924.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 291px; --smush-placeholder-aspect-ratio: 291\/142;\" \/><br \/>\n\u521b\u5efa\u73ed\u7ea7\u8868<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE classes (\n    id CHAR(1) COMMENT \"\u73ed\u7ea7\u4ee3\u53f7\" PRIMARY KEY,\n    name CHAR(3) COMMENT \"\u73ed\u7ea7\u540d\u79f0\"\n) COMMENT \"\u73ed\u7ea7\u8868\";<\/code><\/pre>\n<p>\u63d2\u5165\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">INSERT INTO classes VALUES \n                        (\"1\", \"\u706b\u7bad\u73ed\"),\n                        (\"2\", \"\u5b9e\u9a8c\u73ed\"),\n                        (\"3\", \"\u5e73\u884c\u73ed\");<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704896074277.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 240px; --smush-placeholder-aspect-ratio: 240\/129;\" \/><\/p>\n<p>\u5efa\u7acb\u5916\u952e<\/p>\n<pre><code class=\"language-mysql\">ALTER TABLE student_class\n    ADD CONSTRAINT fk_student_class_id\n    FOREIGN KEY (class_id)\n    REFERENCES classes (id);<\/code><\/pre>\n<h3><span class=\"ez-toc-section\" id=\"%E5%A4%9A%E5%AF%B9%E5%A4%9A\"><\/span>\u591a\u5bf9\u591a<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u4e00\u4e2a\u5b66\u751f\u53ef\u4ee5\u4e0a\u591a\u95e8\u8bfe\uff0c\u6bcf\u95e8\u8bfe\u53ef\u4ee5\u6709\u591a\u4e2a\u5b66\u751f\u4e0a\uff0c\u8fd9\u5c31\u662f\u4e00\u79cd\u591a\u5bf9\u591a\u7684\u5173\u7cfb\u3002<br \/>\n\u9996\u5148\u521b\u5efa\u4e00\u4e2a\u5b66\u751f\u8868<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE stu (\n    id CHAR(1) COMMENT \"\u5b66\u53f7\" PRIMARY KEY,\n    name CHAR(2) COMMENT \"\u59d3\u540d\"\n) COMMENT \"\u5b66\u751f\u8868\";<\/code><\/pre>\n<p>\u63d2\u5165\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">INSERT INTO stu VALUES \n                    (\"1\", \"\u5c0f\u5f3a\"),\n                    (\"2\", \"\u5c0f\u5f20\"),\n                    (\"3\", \"\u5c0f\u7ea2\");<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704894260644.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 229px; --smush-placeholder-aspect-ratio: 229\/142;\" \/><br \/>\n\u518d\u521b\u5efa\u4e00\u4e2a\u8bfe\u7a0b\u8868<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE course (\n    id CHAR(1) COMMENT \"\u8bfe\u7a0b\u4ee3\u53f7\" PRIMARY KEY ,\n    name CHAR(2) COMMENT \"\u8bfe\u7a0b\u540d\u79f0\"\n) COMMENT \"\u8bfe\u7a0b\u8868\";<\/code><\/pre>\n<p>\u63d2\u5165\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">INSERT INTO course VALUES\n                       (\"1\", \"\u9ad8\u6570\"),\n                       (\"2\", \"\u5927\u7269\"),\n                       (\"3\", \"\u82f1\u8bed\");<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704894503815.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 226px; --smush-placeholder-aspect-ratio: 226\/143;\" \/><br \/>\n\u518d\u521b\u5efa\u4e00\u5f20\u8868\uff0c\u5efa\u7acb\u5916\u94fe\u5173\u8054\u4e24\u5f20\u8868<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE stu_course (\n    stu_id CHAR(1) COMMENT \"\u5b66\u53f7\",\n    course_id CHAR(1) COMMENT \"\u8bfe\u7a0b\u4ee3\u53f7\",\n    CONSTRAINT fk_stu_course_stu_id FOREIGN KEY (stu_id) REFERENCES stu(id),\n    CONSTRAINT fk_stu_course_course_id FOREIGN KEY (course_id) REFERENCES course(id)\n) COMMENT \"\u5b66\u751f\u8bfe\u8868\";<\/code><\/pre>\n<p>\u63d2\u5165\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">INSERT INTO stu_course VALUES\n                           (\"1\", \"2\"),\n                           (\"2\", \"1\"),\n                           (\"2\", \"3\"),\n                           (\"3\", \"1\"),\n                           (\"3\", \"2\"),\n                           (\"3\", \"3\");<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704894922824.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 305px; --smush-placeholder-aspect-ratio: 305\/199;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E5%86%85%E8%BF%9E%E6%8E%A5\"><\/span>\u5185\u8fde\u63a5<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u5185\u8fde\u63a5\u4e3b\u8981\u662f\u67e5\u8be2\u4e24\u5f20\u8868\u7684\u4ea4\u96c6\u90e8\u5206\uff0c\u793a\u4f8b\u4f7f\u7528\u4e0a\u9762\u4e00\u5bf9\u591a\u521b\u5efa\u7684\u8868\u3002<\/p>\n<p>\u9690\u5f0f\u5185\u8fde\u63a5<\/p>\n<pre><code class=\"language-mysql\">SELECT \u5b57\u6bb5\u5217\u8868 FROM \u88681, \u88682 WHERE \u6761\u4ef6<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704897310359.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 690px; --smush-placeholder-aspect-ratio: 690\/189;\" \/><\/p>\n<p>\u663e\u5f0f\u5185\u8fde\u63a5<\/p>\n<pre><code class=\"language-mysql\">SELECT \u5b57\u6bb5\u5217\u8868 FROM \u88681 [INNER] JOIN \u88682 ON \u8fde\u63a5\u6761\u4ef6;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704897421474.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 763px; --smush-placeholder-aspect-ratio: 763\/384;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E5%A4%96%E8%BF%9E%E6%8E%A5\"><\/span>\u5916\u8fde\u63a5<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u67e5\u8be2\u5176\u4e2d\u4e00\u5f20\u8868\u53ca\u4e24\u5f20\u8868\u4ea4\u96c6\u7684\u90e8\u5206<br \/>\n\u5de6\u5916\u8fde\u63a5(\u67e5\u8be2\u88681\u53ca\u88681\u548c\u88682\u7684\u4ea4\u96c6\u90e8\u5206)\uff0c\u53f3\u5916\u8fde\u63a5\uff0c\u628a LEFT \u6539\u6210 RIGHT \u5c31\u884c\uff0c\u4e5f\u53ef\u4ee5\u628a\u88681\u548c\u88682\u5bf9\u6362\uff0c\u4e00\u6837\u7684\u6548\u679c<\/p>\n<pre><code class=\"language-mysql\">SELECT \u5b57\u6bb5\u5217\u8868 FROM \u88681 LEFT [OUTER] JOIN \u88682 ON \u6761\u4ef6;<\/code><\/pre>\n<p>\u8fd8\u662f\u4f7f\u7528\u524d\u9762\u4e00\u5bf9\u591a\u521b\u5efa\u7684\u8868\u6f14\u793a<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704897824538.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 801px; --smush-placeholder-aspect-ratio: 801\/204;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704897838226.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 804px; --smush-placeholder-aspect-ratio: 804\/186;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E8%87%AA%E8%BF%9E%E6%8E%A5\"><\/span>\u81ea\u8fde\u63a5<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u53ef\u4ee5\u662f\u5185\u8fde\u63a5\u4e5f\u53ef\u4ee5\u662f\u5916\u8fde\u63a5<\/p>\n<pre><code class=\"language-mysql\">SELECT \u5b57\u6bb5\u5217\u8868 FROM \u8868A \u522b\u540d1 JOIN \u8868A \u522b\u540d2 ON \u6761\u4ef6;<\/code><\/pre>\n<p>\u8fd9\u91cc\u521b\u5efa\u4e00\u5f20\u8868\u7528\u4e8e\u6f14\u793a<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE emp (\n    id TINYINT COMMENT \"\u5de5\u53f7\",\n    name VARCHAR(10) COMMENT \"\u59d3\u540d\",\n    mid TINYINT COMMENT \"\u9886\u5bfc\u7684\u5de5\u53f7\"\n) COMMENT \"\u804c\u5de5\u8868\";<\/code><\/pre>\n<p>\u63d2\u5165\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">INSERT INTO emp VALUES\n                    (1, \"AAA\", NULL),\n                    (2, \"BBB\", 1),\n                    (3, \"CCC\", 1),\n                    (4, \"DDD\", 2),\n                    (5, \"EEE\", 2),\n                    (6, \"FFF\", 3);<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704898756098.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 323px; --smush-placeholder-aspect-ratio: 323\/198;\" \/><\/p>\n<p>\u5185\u8fde\u63a5<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704898925296.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 617px; --smush-placeholder-aspect-ratio: 617\/223;\" \/><\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704899457540.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 626px; --smush-placeholder-aspect-ratio: 626\/228;\" \/><\/p>\n<p>\u5916\u8fde\u63a5<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1704899026765.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 672px; --smush-placeholder-aspect-ratio: 672\/530;\" \/><\/p>\n<p>\u5de6\u5916\u8fde\u63a5\u67e5\u8be2\u7ed3\u679c\u4e2d\uff0c\u5de6\u8fb9\u7f57\u5217\u51fa\u6240\u6709\u804c\u5de5\uff0c\u53f3\u8fb9\u662f\u5bf9\u5e94\u804c\u5de5\u7684\u9886\u5bfc\uff0c\u6ca1\u6709\u9886\u5bfc\u7684\u5c31\u663e\u793a NULL<br \/>\n\u53f3\u5916\u8fde\u63a5\u67e5\u8be2\u7ed3\u679c\u4e2d\uff0c\u53f3\u8fb9\u662f\u7f57\u5217\u51fa\u6240\u6709\u804c\u5de5\uff0c\u5de6\u8fb9\u7ed9\u51fa\u5bf9\u5e94\u7684\u4e0b\u5c5e\uff0c\u6ca1\u6709\u4e0b\u5c5e\u5c31\u663e\u793a NULL<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E8%81%94%E5%90%88%E6%9F%A5%E8%AF%A2\"><\/span>\u8054\u5408\u67e5\u8be2<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-mysql\">UNION [ALL]<\/code><\/pre>\n<p>\u8fd9\u91cc\u968f\u4fbf\u521b\u5efa\u4e86\u4e24\u5f20\u8868\u7528\u4e8e\u6f14\u793a\u67e5\u8be2\uff0c\u4f7f\u7528 UNINO ALL \u4f1a\u76f4\u63a5\u628a\u4e24\u5f20\u8868\u7684\u7ed3\u679c\u62fc\u8d77\u6765<\/p>\n<pre><code class=\"language-mysql\">SELECT * FROM test1\nUNION ALL\nSELECT * FROM test2;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1705392365548.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 240px; --smush-placeholder-aspect-ratio: 240\/138;\" \/><\/p>\n<p>\u5982\u679c\u53bb\u6389 ALL\uff0c\u53ea\u4f7f\u7528 UNINO\uff0c\u5219\u5448\u73b0\u7684\u7ed3\u679c\u662f\u53bb\u9664\u91cd\u590d\u7684<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1705392432707.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 225px; --smush-placeholder-aspect-ratio: 225\/109;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E5%AD%90%E6%9F%A5%E8%AF%A2%E5%B5%8C%E5%A5%97%E6%9F%A5%E8%AF%A2\"><\/span>\u5b50\u67e5\u8be2\/\u5d4c\u5957\u67e5\u8be2<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3><span class=\"ez-toc-section\" id=\"%E6%A0%87%E9%87%8F%E5%AD%90%E6%9F%A5%E8%AF%A2\"><\/span>\u6807\u91cf\u5b50\u67e5\u8be2<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u7528\u67e5\u8be2\u5230\u7684\u4e00\u4e2a\u7ed3\u679c\u4f5c\u4e3a\u6761\u4ef6\u8fdb\u4e00\u6b65\u67e5\u8be2<\/p>\n<p>\u8fd9\u91cc\u4f7f\u7528\u524d\u9762\u521b\u5efa\u7684\u4e24\u5f20\u8868\u6f14\u793a<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1705395299648.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 304px; --smush-placeholder-aspect-ratio: 304\/255;\" \/><\/p>\n<p>\u9996\u5148\u5728\u73ed\u7ea7\u8868\u91cc\u67e5\u8be2\u706b\u7bad\u73ed\u7684 ID\uff0c\u7136\u540e\u518d\u5230\u5b66\u751f\u8868\u4e2d\u67e5\u8be2\u5177\u6709\u8fd9\u4e2a ID \u7684\u5b66\u751f\u4fe1\u606f<\/p>\n<pre><code class=\"language-mysql\">SELECT * FROM student_class\n         WHERE class_id = (SELECT id FROM classes WHERE name = \"\u706b\u7bad\u73ed\");<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1705395467492.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 272px; --smush-placeholder-aspect-ratio: 272\/74;\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E5%88%97%E5%AD%90%E6%9F%A5%E8%AF%A2\"><\/span>\u5217\u5b50\u67e5\u8be2<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u5e38\u7528\u7684\u64cd\u4f5c\u7b26<\/p>\n<pre><code class=\"language-katex\">\\begin{array}{l l}\n\u64cd\u4f5c\u7b26 & \u63cf\u8ff0 \\\\\n\\hline\nIN & \u5728\u6307\u5b9a\u7684\u96c6\u5408\u8303\u56f4\u5185 \\\\\nNOT IN & \u4e0d\u5728\u6307\u5b9a\u7684\u96c6\u5408\u8303\u56f4\u5185 \\\\\nANY & \u5b50\u67e5\u8be2\u8fd4\u56de\u5217\u8868\u4e2d\uff0c\u6709\u4efb\u610f\u4e00\u4e2a\u6ee1\u8db3\u5373\u53ef \\\\\nSOME & \u4e0e ANY \u7b49\u540c\uff0c\u4f7f\u7528 SOME \u7684\u5730\u65b9\u90fd\u53ef\u4ee5\u4f7f\u7528 ANY \\\\\nALL & \u5b50\u67e5\u8be2\u8fd4\u56de\u5217\u8868\u7684\u6240\u6709\u503c\u90fd\u5fc5\u987b\u6ee1\u8db3\n\\end{array}<\/code><\/pre>\n<p>\u524d\u9762\u662f\u5148\u67e5\u8be2\u51fa\u4e00\u4e2a\u7ed3\u679c\uff0c\u518d\u7528\u8fd9\u4e2a\u7ed3\u679c\u4f5c\u4e3a\u6761\u4ef6\u67e5\u8be2\u3002\u5217\u5b50\u67e5\u8be2\u5219\u662f\u67e5\u8be2\u51fa\u7b26\u5408\u67d0\u6761\u4ef6\u7684\u4e00\u5217\u7ed3\u679c\uff0c\u5c06\u8fd9\u4e00\u5217\u7ed3\u679c\u4f5c\u4e3a\u6761\u4ef6\u8fdb\u884c\u67e5\u8be2\u3002<br \/>\n\u6709\u4e0b\u9762\u4e24\u5f20\u8868\uff1a<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1707231542863.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 604px; --smush-placeholder-aspect-ratio: 604\/233;\" \/><br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1707231534714.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 474px; --smush-placeholder-aspect-ratio: 474\/291;\" \/><\/p>\n<p>\u67e5\u8be2\u73ed\u7ea7\u5e73\u5747\u6210\u7ee9\u5927\u4e8e 80 \u7684\u73ed\u7ea7\u4e2d\u7684\u5b66\u751f\u4fe1\u606f<\/p>\n<pre><code class=\"language-mysql\">SELECT * FROM student WHERE class_id in (SELECT class_id\n                                   FROM class\n                                   WHERE average_grades > 80);<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1707231606795.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 472px; --smush-placeholder-aspect-ratio: 472\/163;\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E8%A1%8C%E5%AD%90%E6%9F%A5%E8%AF%A2\"><\/span>\u884c\u5b50\u67e5\u8be2<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u5217\u5b50\u67e5\u8be2\u662f\u540c\u65f6\u7b5b\u9009\u4e00\u5217\u7684\u591a\u884c\uff0c\u884c\u5b50\u67e5\u8be2\u5c31\u662f\u7b5b\u9009\u4e00\u884c\u7684\u591a\u5217\uff08\u591a\u8868\u5934\uff09<br \/>\n\u5728\u4e0a\u9762\u8868\u4e0a\u52a0\u4e0a\u4e2a\u4eba\u5b66\u751f\u6210\u7ee9<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1707235821309.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 645px; --smush-placeholder-aspect-ratio: 645\/285;\" \/><br \/>\n\u73b0\u5728\u8981\u627e\u51fa\u5728\u706b\u7bad\u73ed\u4e2d\u6210\u7ee9\u4e0e\u73ed\u7ea7\u5e73\u5747\u6210\u7ee9\u76f8\u540c\u7684<\/p>\n<pre><code class=\"language-mysql\">SELECT * FROM student WHERE (grades, class_id) = (\n    SELECT average_grades, class_id FROM class WHERE name = '\u706b\u7bad\u73ed');<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1707235881719.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 624px; --smush-placeholder-aspect-ratio: 624\/108;\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E8%A1%A8%E5%AD%90%E6%9F%A5%E8%AF%A2\"><\/span>\u8868\u5b50\u67e5\u8be2<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u7b5b\u9009\u591a\u884c\u591a\u5217<br \/>\n\u5c06\u5b66\u751f\u8868\u4e2d\u5e74\u9f84\u5927\u4e8e 16 \u7684\u6570\u636e\u7b5b\u9009\u51fa\u6765\uff0c\u5c06\u8fd9\u4e9b\u6570\u636e\u548c\u73ed\u7ea7\u8868\u7ed3\u5408\u8d77\u6765\u5916\u8fde\u63a5\u67e5\u8be2<\/p>\n<pre><code class=\"language-mysql\">SELECT s.name, c.name FROM (SELECT * FROM student WHERE age > 16) s LEFT JOIN class c on s.class_id = c.class_id;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1707379502906.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 355px; --smush-placeholder-aspect-ratio: 355\/181;\" \/><\/p>\n<h1><span class=\"ez-toc-section\" id=\"%E4%BA%8B%E5%8A%A1\"><\/span>\u4e8b\u52a1<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>MySQL \u4e2d\u9ed8\u8ba4\u6bcf\u6b21\u6267\u884c\u4fee\u6539\u6570\u636e\u6307\u4ee4\u540e\u4f1a\u7acb\u5373\u63d0\u4ea4\uff08\u9ed8\u8ba4\u81ea\u52a8\u4e8b\u52a1\uff09\uff0c\u4f46\u662f\u8fd9\u79cd\u60c5\u666f\u4e2d\uff08A\u5411B\u8f6c\u8d26\uff0c\u9996\u5148\u67e5\u8be2A\u7684\u4f59\u989d\uff0c\u4f59\u989d\u8db3\u591f\uff0c\u4eceA\u7684\u4f59\u989d\u6263\u9664\uff0c\u518d\u7ed9B\u589e\u52a0\u4f59\u989d\uff09\uff0c\u53ef\u80fd\u5c31\u4f1a\u51fa\u73b0\u95ee\u9898\uff08\u5982\u679c\u5728A\u6263\u9664\u4f59\u989d\u540e\u548c\u5728B\u589e\u52a0\u4f59\u989d\u4e4b\u95f4\u7684\u64cd\u4f5c\u4e2d\u51fa\u73b0\u5f02\u5e38\u5bfc\u81f4\u7ec8\u6b62\uff09\uff0c\u8fd9\u79cd\u60c5\u5f62\u4e0bA\u7684\u4f59\u989d\u6263\u4e86\uff0c\u4f46\u662fB\u7684\u4f59\u989d\u6ca1\u6709\u589e\u52a0\u3002<br \/>\nMySQL \u4e2d\u7684\uff08\u624b\u52a8\uff09\u4e8b\u52a1\u5219\u53ef\u4ee5\u5e94\u5bf9\u8fd9\u4e2a\u60c5\u51b5\uff0c\u53ef\u4ee5\u5c06\u6574\u4e2a\u6d41\u7a0b\u64cd\u4f5c\u4f5c\u4e3a\u4e00\u4e2a\u4e8b\u52a1\uff08\u67e5\u8be2A\u4f59\u989d\uff0c\u6263\u9664A\u4f59\u989d\uff0c\u589e\u52a0B\u4f59\u989d\uff09\uff0c\u4e2d\u95f4\u7684\u64cd\u4f5c\u4e0d\u4f1a\u6700\u7ec8\u4fee\u6539\u539f\u59cb\u6570\u636e\uff0c\u53ea\u662f\u6682\u5b58\uff0c\u64cd\u4f5c\u6210\u529f\u6700\u540e\u63d0\u4ea4\u4fee\u6539\u5c31\u884c\uff0c\u64cd\u4f5c\u5931\u8d25\u653e\u5f03\u6682\u5b58\u7684\u64cd\u4f5c\uff0c\u539f\u59cb\u6570\u636e\u4e0d\u4fee\u6539\uff08\u56de\u6eda\uff09\u3002<\/p>\n<p>\u521b\u5efa\u7528\u4e8e\u6d4b\u8bd5\u7684\u8868<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE account(\n    name varchar(2),\n    balance int\n);\n\nINSERT into account VALUES\n                        ('\u5c0f\u660e', 2000),\n                        ('\u5c0f\u7ea2', 2000);<\/code><\/pre>\n<p>\u6062\u590d\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">UPDATE account set balance = 2000 WHERE name = '\u5c0f\u660e' or name = '\u5c0f\u7ea2';<\/code><\/pre>\n<p>\u67e5\u770b\u4e8b\u52a1\u63d0\u4ea4\u65b9\u5f0f<br \/>\n0 \u4e3a\u624b\u52a8\uff0c1 \u4e3a\u81ea\u52a8<\/p>\n<pre><code class=\"language-mysql\">SELECT @@autocommit;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1707738758873.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 191px; --smush-placeholder-aspect-ratio: 191\/71;\" \/><\/p>\n<p>\u6539\u4e3a\u624b\u52a8\u5c31\u628a\u8fd9\u4e2a\u53d8\u91cf\u503c\u8bbe\u7f6e\u4e3a 0<\/p>\n<pre><code class=\"language-mysql\">SET @@autocommit = 0;<\/code><\/pre>\n<p>\u63d0\u4ea4\u4e8b\u52a1<br \/>\n\u5728\u624b\u52a8\u4e8b\u52a1\u72b6\u6001(\u6216\u663e\u5f0f\u542f\u7528\u4e8b\u52a1)\u4e0b\uff0c\u6267\u884c\u4e86\u4fee\u6539\u64cd\u4f5c\u4e0d\u4f1a\u76f4\u63a5\u4fee\u6539\uff0c\u5728\u6267\u884c\u5b8c\u6bcf\u4e2a\u6307\u4ee4\u6216\u8005\u4e00\u7cfb\u5217\u6307\u5b9a\u540e\u624b\u52a8\u6267\u884c\u8fd9\u4e2a\u6307\u4ee4\u624d\u4f1a\u63d0\u4ea4\u751f\u6548<\/p>\n<pre><code class=\"language-mysql\">COMMIT;<\/code><\/pre>\n<p>\u56de\u6eda\u4e8b\u52a1<\/p>\n<pre><code class=\"language-mysql\">ROLLBACK;<\/code><\/pre>\n<p>\u663e\u5f0f\u542f\u7528\u4e8b\u52a1<\/p>\n<pre><code class=\"language-mysql\">start transaction;<\/code><\/pre>\n<hr \/>\n<p>\u8f6c\u8d26\u6a21\u62df\u5b9e\u73b0<\/p>\n<pre><code class=\"language-mysql\"># \u67e5\u8be2\u4f59\u989d\nSELECT * FROM account;\n\n# \u5c0f\u660e\u4f59\u989d -1000\nUPDATE account SET balance = balance - 1000 WHERE name = '\u5c0f\u660e';\n\n# \u5c0f\u7ea2\u4f59\u989d +1000\nUPDATE account SET balance = balance + 1000 WHERE name = '\u5c0f\u7ea2';\n\n# \u67e5\u8be2\u4f59\u989d\nSELECT * FROM account;<\/code><\/pre>\n<p>\u6a21\u62df\u5f02\u5e38<br \/>\n\u6211\u5728\u5c0f\u660e\u6263\u9664\u8f6c\u51fa\u91d1\u989d\u6838\u5c0f\u7ea2\u589e\u52a0\u91d1\u989d\u4e2d\u95f4\u6dfb\u52a0\u4e86\u4e00\u4e2a\u9519\u8bef\u7684\u8bed\u53e5<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1707740515649.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 174px; --smush-placeholder-aspect-ratio: 174\/174;\" \/><\/p>\n<p>\u8fd9\u6837\u5c31\u51fa\u73b0\u4e86\u5c0f\u660e\u4f59\u989d\u6263\u9664\uff0c\u4f46\u662f\u5c0f\u7ea2\u4f59\u989d\u6ca1\u6709\u589e\u52a0\u7684\u60c5\u51b5<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/01\/image-1707740559770.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 290px; --smush-placeholder-aspect-ratio: 290\/103;\" \/><\/p>\n<hr \/>\n<p>\u53ef\u4ee5\u663e\u5f0f\u542f\u7528\u4e8b\u52a1\uff0c\u5728\u64cd\u4f5c\u65f6\u9047\u5230\u5f02\u5e38\u5c31\u6267\u884c\u56de\u6eda\uff0c\u5219\u4f1a\u6062\u590d\u539f\u6570\u636e\u5e76\u7ed3\u675f\u5f53\u524d\u4e8b\u52a1\u3002<\/p>\n<p>\u4e8b\u52a1\u8fd9\u4e2a\u8bbe\u8ba1\u6709\u70b9\u50cf Git\uff0c\u6dfb\u52a0\u5220\u9664\u4fee\u6539\u7b49\u64cd\u4f5c\u540e\u53ea\u662f\u6dfb\u52a0\u5230\u6682\u5b58\u533a\uff0c\u6700\u7ec8\u64cd\u4f5c\u5b8c\u4f7f\u7528 commit \u624d\u63d0\u4ea4\u3002\u53ea\u662f MySQL \u9ed8\u8ba4\u72b6\u6001\u6bcf\u6267\u884c\u4e00\u6b21\u64cd\u4f5c\u5c31\u4f1a\u81ea\u52a8\u63d0\u4ea4\u4e00\u6b21\uff0c\u8bbe\u7f6e\u663e\u5f0f\u4e8b\u52a1\u540e\uff0c\u5219\u4e0d\u4f1a\u81ea\u52a8\u63d0\u4ea4\uff0c\u4e2d\u95f4\u53ef\u4ee5\u56de\u6eda\u653e\u5f03\u4fee\u6539\u3002<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E7%89%B9%E6%80%A7%EF%BC%88ACID%EF%BC%89\"><\/span>\u7279\u6027\uff08ACID\uff09<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<ul>\n<li>\u539f\u5b50\u6027\uff08Atomicity\uff09<\/li>\n<\/ul>\n<p>\u4e8b\u52a1\u662f\u6700\u5c0f\u7684\u64cd\u4f5c\u5355\u5143\uff0c\u4e00\u4e2a\u4e8b\u52a1\u53ef\u4ee5\u662f\u4e00\u4e2a\u64cd\u4f5c\u6216\u8005\u591a\u4e2a\u64cd\u4f5c\u7684\u96c6\u5408\uff08\u4f46\u4e0d\u53ef\u5206\u5272\uff09\uff0c\u5176\u4e2d\u4efb\u4e00\u7ec4\u5458\u6267\u884c\u5931\u8d25\u5c31\u662f\u6574\u4e2a\u4e8b\u52a1\u7684\u5931\u8d25\uff0c\u800c\u5168\u90e8\u6267\u884c\u6210\u529f\uff0c\u4e8b\u52a1\u624d\u6267\u884c\u6210\u529f\u3002<\/p>\n<ul>\n<li>\u4e00\u81f4\u6027\uff08Consistency\uff09<\/li>\n<\/ul>\n<p>\u4e00\u81f4\u6027\u53ef\u4ee5\u4f53\u73b0\u5728\u4e0a\u9762\u7684\u8f6c\u8d26\u6848\u4f8b\u4e2d\uff0c\u5c0f\u660e\u8f6c\u51fa\u4e86\u94b1\uff0c\u4f59\u989d\u51cf\u5c11\u4e86\uff0c\u8f6c\u7ed9\u5c0f\u7ea2\u4e86\uff0c\u5c0f\u7ea2\u4f59\u989d\u5bf9\u5e94\u589e\u52a0\u4e86\uff0c\u4e0d\u4f1a\u51fa\u73b0\u5c0f\u660e\u4f59\u989d\u51cf\u5c11\u4e86\uff0c\u4f46\u5c0f\u7ea2\u4f59\u989d\u6ca1\u6709\u589e\u52a0\u7684\u60c5\u51b5\u3002<\/p>\n<ul>\n<li>\u9694\u79bb\u6027\uff08Isolation\uff09<\/li>\n<\/ul>\n<p>\u591a\u4e2a\u4e8b\u52a1\u5e76\u53d1\u6267\u884c\u65f6\u4e92\u4e0d\u5f71\u54cd\uff0c\u5404\u81ea\u72ec\u7acb\u6267\u884c\u3002<\/p>\n<ul>\n<li>\u6301\u4e45\u6027\uff08Durability\uff09<\/li>\n<\/ul>\n<p>\u4e8b\u52a1\u88ab\u63d0\u4ea4\uff08\u6216\u56de\u6eda\uff09\u5bf9\u6570\u636e\u7684\u4fee\u6539\u5c31\u662f\u6c38\u4e45\u7684\uff0c\u5199\u5165\u4e86\u786c\u76d8\u4e2d\u7684\u6570\u636e\u5e93\u6587\u4ef6\u91cc\u4e86\u3002<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E5%B9%B6%E5%8F%91%E4%BA%8B%E5%8A%A1%E5%AD%98%E5%9C%A8%E7%9A%84%E9%97%AE%E9%A2%98\"><\/span>\u5e76\u53d1\u4e8b\u52a1\u5b58\u5728\u7684\u95ee\u9898<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<ul>\n<li>\n<p>\u810f\u8bfb<br \/>\n\u4e00\u4e2a\u4e8b\u52a1\u8bfb\u5230\u53e6\u5916\u4e00\u4e2a\u4e8b\u52a1\u8fd8\u6ca1\u6709\u63d0\u4ea4\u7684\u6570\u636e<\/p>\n<\/li>\n<li>\n<p>\u4e0d\u53ef\u91cd\u590d\u8bfb<br \/>\n\u4e00\u4e2a\u4e8b\u52a1\u5148\u540e\u8bfb\u53d6\u540c\u4e00\u6761\u8bb0\u5f55\uff0c\u4f46\u4e24\u6b21\u8bfb\u53d6\u7684\u6570\u636e\u4e0d\u540c\u3002\u4e00\u4e2a\u4e8b\u52a1\u6709\u4e24\u4e2a\u8bfb\u53d6\u64cd\u4f5c\uff0c\u7b2c\u4e00\u6b21\u8bfb\u53d6\u540e\uff0c\u5728\u7b2c\u4e8c\u6b21\u8bfb\u53d6\u524d\uff0c\u53e6\u5916\u4e00\u4e2a\u4e8b\u52a1\u5bf9\u6570\u636e\u8fdb\u884c\u4e86\u4fee\u6539\uff0c\u7b2c\u4e8c\u6b21\u8bfb\u53d6\u65f6\u6570\u636e\u5c31\u548c\u7b2c\u4e00\u6b21\u4e0d\u4e00\u6837\u4e86\u3002<\/p>\n<\/li>\n<li>\n<p>\u5e7b\u8bfb<br \/>\n\u4e00\u4e2a\u4e8b\u52a1\u5728\u8bfb\u53d6\u6570\u636e\u65f6\uff0c\u6ca1\u6709\u5bf9\u5e94\u7684\u6570\u636e\uff0c\u5c1d\u8bd5\u63d2\u5165\u6570\u636e\u7684\u65f6\u5019\u53d1\u73b0\u5df2\u7ecf\u5b58\u5728\u4e86\u3002\u4e00\u4e2a\u4e8b\u52a1\u5728\u8bfb\u53d6\u64cd\u4f5c\u7684\u65f6\u5019\u53d1\u73b0\u6570\u636e\u4e0d\u5b58\u5728\uff0c\u7136\u540e\u51c6\u5907\u63d2\u5165\u6570\u636e\uff0c\u5728\u63d2\u5165\u4e4b\u524d\u53e6\u5916\u4e00\u4e2a\u4e8b\u52a1\u5148\u6267\u884c\u4e86\u63d2\u5165\uff0c\u7b49\u5230\u539f\u4e8b\u52a1\u6253\u7b97\u63d2\u5165\u7684\u65f6\u5019\u53c8\u53d1\u73b0\u5df2\u7ecf\u5b58\u5728\u3002<\/p>\n<\/li>\n<\/ul>\n<h2><span class=\"ez-toc-section\" id=\"%E4%BA%8B%E5%8A%A1%E9%9A%94%E7%A6%BB%E7%BA%A7%E5%88%AB\"><\/span>\u4e8b\u52a1\u9694\u79bb\u7ea7\u522b<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<pre><code class=\"language-katex\">\\begin{array}{l}\n\u9694\u79bb\u7ea7\u522b & \u810f\u8bfb & \u4e0d\u53ef\u91cd\u590d\u8bfb & \u5e7b\u8bfb \\\\\nREAD\\ UNCOMMITTED & &# & &# & &# \\\\\nREAD\\ COMMITTED & &# & &# & &# \\\\\nREPEATABLE\\ READ(\u9ed8\u8ba4) & &# & &# & &# \\\\\nSERIALIZABLE & &# & &# & &#\n\\end{array}<\/code><\/pre>\n<p>\u67e5\u770b\u4e8b\u52a1\u9694\u79bb\u7ea7\u522b<\/p>\n<pre><code class=\"language-mysql\">SELECT @@TRANSACTION_ISOLATION;<\/code><\/pre>\n<p>\u8bbe\u7f6e\u4e8b\u52a1\u9694\u79bb\u7ea7\u522b<\/p>\n<pre><code class=\"language-mysql\">SET \u4f5c\u7528\u8303\u56f4 TRANSACTION ISOLATION LEVEL \u9694\u79bb\u7ea7\u522b;<\/code><\/pre>\n<p>\u4f5c\u7528\u8303\u56f4\u53ef\u4ee5\u5199 SESSION\uff08\u53ea\u5728\u5f53\u524d\u5ba2\u6237\u7aef\u751f\u6548\uff09\u548c GLOBAL\uff08\u5168\u5c40\uff09<\/p>\n<h1><span class=\"ez-toc-section\" id=\"%E5%AD%98%E5%82%A8%E5%BC%95%E6%93%8E\"><\/span>\u5b58\u50a8\u5f15\u64ce<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>\u67e5\u770b\u4e00\u4e0b\u524d\u9762\u521b\u5efa\u7684\u4e00\u5f20\u8868\u7684\u521b\u5efa\u8bed\u53e5\uff0c\u5f53\u65f6\u5e76\u6ca1\u6709\u663e\u5f0f\u6307\u5b9a\u5f15\u64ce\uff0cMySQL \u81ea\u52a8\u6307\u5b9a\u7684 InnoDB\uff0c\u5373\u9ed8\u8ba4\u5f15\u64ce\u662f\u8fd9\u4e2a\u3002<br \/>\n\u521b\u5efa\u8868\u7684\u65f6\u5019\u8981\u663e\u5f0f\u6307\u5b9a\u5f15\u64ce\u53ef\u4ee5\u53c2\u8003\u8fd9\u4e2a\u8bed\u53e5<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1707917815341.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 651px; --smush-placeholder-aspect-ratio: 651\/310;\" \/><\/p>\n<p>\u67e5\u770b\u5f53\u524d MySQL \u7248\u672c\u652f\u6301\u7684\u5f15\u64ce\u6709\u90a3\u4e9b<\/p>\n<pre><code class=\"language-mysql\">SHOW ENGINES ;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708078185183.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 1212px; --smush-placeholder-aspect-ratio: 1212\/320;\" \/><\/p>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|l|l|}\n\\hline\n\u7279\u70b9 & InnoDB & MyISAM & Memory \\\\\n\\hline\n\u4e8b\u52a1\u5b89\u5168 & \u652f\u6301 & - & - \\\\\n\u9501\u673a\u5236 & \u884c\u9501 & \u8868\u9501 &\u8868\u9501 \\\\\nB+tree\u7d22\u5f15 & \u652f\u6301 & \u652f\u6301 & \u652f\u6301 \\\\\nHash\u7d22\u5f15 & - & - & \u652f\u6301 \\\\\n\u5168\u6587\u7d22\u5f15 & \u652f\u6301\uff085.6\u7248\u672c\u4e4b\u540e\uff09& \u652f\u6301 & - \\\\\n\u7a7a\u95f4\u4f7f\u7528 & \u9ad8 & \u4f4e & N\/A \\\\\n\u5185\u5b58\u4f7f\u7528 & \u9ad8 & \u4f4e & \u4e2d\u7b49 \\\\\n\u6279\u91cf\u63d2\u5165\u901f\u5ea6 & \u4f4e & \u9ad8 & \u9ad8 \\\\\n\u652f\u6301\u5916\u952e & \u652f\u6301 & - & - \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<ul>\n<li>\n<p>InnoDB\uff1aMySQL \u7684\u9ed8\u8ba4\u5b58\u50a8\u5f15\u64ce\uff0c\u652f\u6301\u4e8b\u52a1\u3001\u5916\u952e\u3002\u5982\u679c\u5bf9\u4e8b\u52a1\u7684\u5b8c\u6574\u6027\u6709\u6bd4\u8f83\u9ad8\u7684\u8981\u6c42\uff0c\u5728\u5e76\u53d1\u6761\u4ef6\u4e0b\u8981\u6c42\u6570\u636e\u7684\u4e00\u81f4\u6027\u3002\u53e6\u5916\u5bf9\u6570\u636e\u7684\u64cd\u4f5c\u9664\u4e86\u63d2\u5165\u548c\u67e5\u8be2\u4e4b\u5916\uff0c\u8fd8\u5305\u542b\u5f88\u591a\u7684\u66f4\u65b0\u3001\u5220\u9664\u64cd\u4f5c\uff0c\u90a3\u4e48\u9009\u62e9\u8fd9\u4e2a\u5f15\u64ce\u6bd4\u8f83\u5408\u9002\u3002<\/p>\n<\/li>\n<li>\n<p>MyISAM\uff1a\u5982\u679c\u662f\u4ee5\u8bfb\u53d6\u548c\u63d2\u5165\u64cd\u4f5c\u4e3a\u4e3b\uff0c\u53ea\u6709\u5f88\u5c11\u7684\u66f4\u65b0\u548c\u5220\u9664\u64cd\u4f5c\uff0c\u5e76\u4e14\u5bf9\u4e8b\u52a1\u7684\u5b8c\u6574\u6027\u3001\u5e76\u53d1\u6027\u8981\u6c42\u4e0d\u662f\u5f88\u9ad8\uff0c\u90a3\u4e48\u53ef\u4ee5\u9009\u62e9\u8fd9\u4e2a\u5f15\u64ce\u3002<\/p>\n<\/li>\n<li>\n<p>MEMORY\uff1a\u6240\u6709\u6570\u636e\u90fd\u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\uff0c\u8bbf\u95ee\u901f\u5ea6\u5feb\uff0c\u901a\u5e38\u7528\u4e8e\u4e34\u65f6\u8868\u53ca\u7f13\u5b58\u3002\u4e0d\u8fc7\u5b58\u5728\u4e00\u5b9a\u7684\u7f3a\u9677\uff0c\u5bf9\u8868\u7684\u5927\u5c0f\u6709\u9650\u5236\uff0c\u592a\u5927\u7684\u8868\u65e0\u6cd5\u5b58\u50a8\u5728\u5185\u5b58\u4e2d\uff0c\u5e76\u4e14\u65e0\u6cd5\u4fdd\u969c\u6570\u636e\u7684\u5b89\u5168\u6027\uff08\u610f\u5916\u65ad\u7535\u3001\u5b95\u673a\u7b49\u53ef\u80fd\u9020\u6210\u6570\u636e\u4e22\u5931\uff09<\/p>\n<\/li>\n<\/ul>\n<h1><span class=\"ez-toc-section\" id=\"%E7%B4%A2%E5%BC%95_%E2%80%93_%E6%9F%A5%E8%AF%A2%E4%BC%98%E5%8C%96\"><\/span>\u7d22\u5f15 &#8211; \u67e5\u8be2\u4f18\u5316<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|}\n\\hline\n\u7d22\u5f15\u7ed3\u6784 & \u63cf\u8ff0 \\\\\n\\hline\nB+Tree & \u6700\u5e38\u89c1\u7684\u7d22\u5f15\u7c7b\u578b\uff0c\u5927\u90e8\u5206\u5b58\u50a8\u5f15\u64ce\u90fd\u652f\u6301\u3002 \\\\\nHash\u7d22\u5f15 & \u5e95\u5c42\u6570\u636e\u7ed3\u6784\u662f\u7528\u54c8\u5e0c\u8868\u5b9e\u73b0\u7684\uff0c\u53ea\u6709\u7cbe\u786e\u5339\u914d\u7d22\u5f15\u5217\u7684\u67e5\u8be2\u624d\u6709\u6548\uff0c\u4e0d\u652f\u6301\u8303\u56f4\u67e5\u8be2\u3002\\\\\nR-tree & \u8fd9\u662f MyISAM \u5f15\u64ce\u7684\u4e00\u4e2a\u7279\u6b8a\u7d22\u5f15\u7c7b\u578b\uff0c\u4e3b\u8981\u7528\u4e8e\u5730\u7406\u7a7a\u95f4\u6570\u636e\u7c7b\u578b\uff0c\u4f7f\u7528\u8f83\u5c11\u3002 \\\\\nFull-text & \u901a\u8fc7\u5efa\u7acb\u5012\u6392\u7d22\u5f15\uff0c\u5feb\u901f\u5339\u914d\u6587\u6863\u7684\u65b9\u5f0f\u3002\\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|l|l|}\n\\hline\n\u7d22\u5f15 & InnoDB & MyISAM & Memory \\\\\n\\hline\nB+tree & \u652f\u6301 & \u652f\u6301 & \u652f\u6301 \\\\\nHash & \u4e0d\u652f\u6301 & \u4e0d\u652f\u6301 & \u652f\u6301 \\\\\nR-tree & \u4e0d\u652f\u6301 & \u652f\u6301 & \u4e0d\u652f\u6301 \\\\\nFull-text & \u652f\u6301\uff085.6\u7248\u672c\u540e\uff09 & \u652f\u6301 & \u4e0d\u652f\u6301 \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<hr \/>\n<p>\u6570\u636e\u7ed3\u6784\u53ef\u89c6\u5316\uff1a<a href=\"https:\/\/iyatt.com\/tools\/DataStructureVisualizations\/Algorithms.html\">https:\/\/iyatt.com\/tools\/DataStructureVisualizations\/Algorithms.html<\/a><\/p>\n<p>B+tree \u4f9d\u6b21\u63d2\u5165100\u300165\u3001169\u3001368\u3001900\u3001556\u3001780\u300135\u3001215\u30011200\u3001234\u3001888\u3001158\u300190\u30011000\u300188\u3001120\u3001268\u3001250<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/20240217_201407.gif\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 700px; --smush-placeholder-aspect-ratio: 700\/127;\" \/><\/p>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|l|l|}\n\\hline\n\u5206\u7c7b & \u542b\u4e49 & \u7279\u70b9 & \u5173\u952e\u5b57 \\\\\n\\hline\n\u4e3b\u952e\u7d22\u5f15 & \u9488\u5bf9\u8868\u4e2d\u4e3b\u952e\u521b\u5efa\u7684\u7d22\u5f15 & \u9ed8\u8ba4\u81ea\u52a8\u81ea\u52a8\u521b\u5efa\uff0c\u53ea\u6709\u4e00\u4e2a & PRIMARY \\\\\n\u552f\u4e00\u7d22\u5f15 & \u907f\u514d\u540c\u4e00\u4e2a\u8868\u4e2d\u67d0\u5217\u6570\u636e\u91cd\u590d & \u53ef\u4ee5\u6709\u591a\u4e2a & UNIQUE \\\\\n\u5e38\u89c4\u7d22\u5f15 & \u5feb\u901f\u5b9a\u4f4d\u7279\u5b9a\u6570\u636e & \u53ef\u4ee5\u6709\u591a\u4e2a &  \\\\\n\u5168\u6587\u7d22\u5f15 & \u5168\u6587\u7d22\u5f15\u67e5\u627e\u7684\u662f\u6587\u672c\u4e2d\u7684\u5173\u952e\u8bcd\uff0c\u800c\u4e0d\u662f\u6bd4\u8f83\u7d22\u5f15\u4e2d\u7684\u503c & \u53ef\u4ee5\u6709\u591a\u4e2a & FULLTEXT \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<p>\u5728 InnoDB \u4e2d<\/p>\n<pre><code class=\"language-katex\">\\begin{array}{|l|l|l|}\n\\hline\n\u5206\u7c7b & \u542b\u4e49 & \u7279\u70b9 \\\\\n\\hline\n\u805a\u96c6\u7d22\u5f15\uff08Clustered Index\uff09 & \u5c06\u6570\u636e\u5b58\u50a8\u4e0e\u7d22\u5f15\u653e\u5728\u4e86\u4e00\u5757\uff0c\u7d22\u5f15\u7ed3\u6784\u7684\u53f6\u5b50\u8282\u70b9\u4fdd\u5b58\u4e86\u884c\u6570\u636e & \u5fc5\u987b\u6709\uff0c\u4e14\u53ea\u6709\u4e00\u4e2a \\\\\n\u4e8c\u7ea7\u7d22\u5f15\uff08Secondary Index\uff09 & \u5c06\u6570\u636e\u548c\u7d22\u5f15\u5206\u5f00\u5b58\u50a8\uff0c\u7d22\u5f15\u7ed3\u6784\u7684\u53f6\u5b50\u8282\u70b9\u5173\u8054\u7684\u662f\u5bf9\u5e94\u7684\u4e3b\u952e & \u53ef\u4ee5\u5b58\u5728\u591a\u4e2a \\\\\n\\hline\n\\end{array}<\/code><\/pre>\n<p>\u805a\u96c6\u7d22\u5f15\u9009\u53d6\u89c4\u5219\uff1a<\/p>\n<ul>\n<li>\u5982\u679c\u5b58\u5728\u4e3b\u952e\uff0c\u4e3b\u952e\u7d22\u5f15\u5c31\u662f\u805a\u96c6\u7d22\u5f15<\/li>\n<li>\u5982\u679c\u4e0d\u5b58\u5728\u4e3b\u952e\uff0c\u5c06\u4f7f\u7528\u7b2c\u4e00\u4e2a\u552f\u4e00\u7d22\u5f15\u4f5c\u4e3a\u805a\u96c6\u7d22\u5f15<\/li>\n<li>\u5982\u679c\u524d\u4e24\u8005\u90fd\u6ca1\u6709\u5408\u9002\u7684\uff0c\u5219 InnoDB \u4f1a\u81ea\u52a8\u751f\u6210\u4e00\u4e2a rowid \u4f5c\u4e3a\u9690\u85cf\u7684\u805a\u96c6\u7d22\u5f15<\/li>\n<\/ul>\n<p>\u521b\u5efa\u7d22\u5f15<br \/>\n\uff08\u5982\u679c\u8981\u521b\u5efa\u5e38\u89c4\u7d22\u5f15\uff0c\u5219\u4e0d\u6307\u5b9a UNIQUE \u6216 FULLTEXT\uff09<\/p>\n<pre><code class=\"language-mysql\">CREATE [UNIQUE | FULLTEXT] INDEX \u7d22\u5f15\u540d ON \u8868\u540d (\u7d22\u5f15\u5217\u540d);<\/code><\/pre>\n<p>\u67e5\u770b\u7d22\u5f15<\/p>\n<pre><code class=\"language-mysql\">SHOW INDEX FROM \u8868\u540d;<\/code><\/pre>\n<p>\u5220\u9664\u7d22\u5f15<\/p>\n<pre><code class=\"language-mysql\">DROP INDEX \u7d22\u5f15\u540d ON \u8868\u540d;<\/code><\/pre>\n<h2><span class=\"ez-toc-section\" id=\"%E8%AF%AD%E6%B3%95\"><\/span>\u8bed\u6cd5<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u521b\u5efa\u4e00\u5f20\u8868\uff0c\u521b\u5efa\u8bed\u53e5\u4f7f\u7528\uff1a<a href=\"https:\/\/blog.iyatt.com\/?p=12631#_%E4%B8%80%E8%88%AC%E7%BA%A6%E6%9D%9F%E7%A4%BA%E4%BE%8B\">https:\/\/blog.iyatt.com\/?p=12631#_%E4%B8%80%E8%88%AC%E7%BA%A6%E6%9D%9F%E7%A4%BA%E4%BE%8B<\/a><br \/>\n\u67e5\u770b\u8fd9\u5f20\u8868\u7684\u7d22\u5f15<br \/>\n\uff08\u52a0\u4e0a <strong>\\G<\/strong> \u4f1a\u6309\u884c\u663e\u793a\uff09<\/p>\n<pre><code class=\"language-mysql\">SHOW INDEX FROM new_user\\G;<\/code><\/pre>\n<p>\u53ef\u4ee5\u770b\u5230\u5217\u540d id \u7684 Key_name \u662f PRIMARY \u4e3b\u952e\u7d22\u5f15\uff08\u521b\u5efa\u8868\u6307\u5b9a\u4e86\u4e3b\u952e\u7ea6\u675f\uff09\uff0c\u5217\u540d name \u7684 Key_name  \u5c31\u662f\u5217\u540d\uff0c\u8be5\u5217\u5728\u521b\u5efa\u8868\u65f6\u6307\u5b9a\u4e86\u552f\u4e00\u7ea6\u675f\uff0c\u5176\u5b83\u5217\u5219\u6ca1\u6709\u7d22\u5f15\u3002<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708225810389.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 588px; --smush-placeholder-aspect-ratio: 588\/665;\" \/><\/p>\n<p>\u73b0\u5728\u624b\u52a8\u4e3a age \u5217\u521b\u5efa\u4e00\u4e2a\u5e38\u89c4\u7d22\u5f15\u540d\u4e3a index_age<\/p>\n<pre><code class=\"language-mysql\">CREATE INDEX index_age ON new_user(age);<\/code><\/pre>\n<p>\u518d\u6b21\u67e5\u770b\u53ef\u4ee5\u770b\u5230 age \u5217\u7684\u7d22\u5f15<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708226172583.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 300px; --smush-placeholder-aspect-ratio: 300\/324;\" \/><\/p>\n<p>\u5220\u9664\u521b\u5efa\u7684\u5e38\u89c4\u7d22\u5f15<\/p>\n<pre><code class=\"language-mysql\">DROP INDEX index_age ON new_user;<\/code><\/pre>\n<p>\u518d\u6b21\u4e3a age \u548c status \u540c\u65f6\u521b\u5efa\u4e00\u4e2a\u552f\u4e00\u7d22\u5f15\uff08\u8054\u5408\u7d22\u5f15\uff09<\/p>\n<pre><code class=\"language-mysql\">CREATE UNIQUE INDEX index_age ON new_user(age, status);<\/code><\/pre>\n<p>\u67e5\u770b\u7d22\u5f15<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708227883772.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 279px; --smush-placeholder-aspect-ratio: 279\/634;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E6%80%A7%E8%83%BD%E5%88%86%E6%9E%90\"><\/span>\u6027\u80fd\u5206\u6790<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3><span class=\"ez-toc-section\" id=\"%E6%9F%A5%E8%AF%A2_SQL_%E6%89%A7%E8%A1%8C%E9%A2%91%E6%AC%A1\"><\/span>\u67e5\u8be2 SQL \u6267\u884c\u9891\u6b21<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u67e5\u8be2\u72b6\u6001\u4fe1\u606f<\/p>\n<pre><code class=\"language-mysql\">SHOW [SESSIOn | GLOBAL] STATUS;<\/code><\/pre>\n<p>\u7b5b\u9009\u51fa SQL \u8bed\u53e5\u6267\u884c\u6b21\u6570\uff0c\u5168\u5c40\u67e5\u8be2\u542b\u6709 Com \u7684\u4e14\u540e\u7eed\u8fd8\u6709 7 \u4e2a\u5b57\u6bcd\u7684\u53d8\u91cf\uff0c\u7528 7 \u4e2a\u4e0b\u5212\u7ebf _ \u5339\u914d<\/p>\n<pre><code class=\"language-mysql\">SHOW GLOBAL STATUS LIKE 'Com_______';<\/code><\/pre>\n<p>\u8fd9\u91cc\u6211\u5728\u5f53\u524d\u535a\u5ba2\u7684\u670d\u52a1\u5668\u6570\u636e\u5e93\u4e0a\u67e5\u8be2\uff08Mariadb \u548c MySQL \u57fa\u672c\u4e0a\u517c\u5bb9\uff09<br \/>\n\u53ef\u4ee5\u770b\u5230\u63d2\u5165\u4e86 948768 \u6b21\uff0c\u5220\u9664\u4e86 339467 \u6b21\uff0c\u67e5\u8be2\u4e86 34850658 \u6b21\uff0c\u4fee\u6539\u4e86 667195 \u6b21\u3002\u53ef\u4ee5\u770b\u5230\u91cc\u9762\u67e5\u8be2\u6b21\u6570\u662f\u6700\u591a\u7684\uff0c\u6bd5\u7adf\u535a\u5ba2\u5927\u591a\u6570\u65f6\u5019\u90fd\u662f\u6d4f\u89c8\u67e5\u770b\uff0c\u6240\u4ee5\u4f18\u5316\u7684\u91cd\u70b9\u5c31\u5728\u67e5\u8be2\u4e0a\u3002<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708232981687.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 419px; --smush-placeholder-aspect-ratio: 419\/253;\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E6%85%A2%E6%9F%A5%E8%AF%A2%E6%97%A5%E5%BF%97\"><\/span>\u6162\u67e5\u8be2\u65e5\u5fd7<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u5f53 MySQL \u4e2d\u67d0\u4e2a\u8bed\u53e5\u6267\u884c\u8d85\u8fc7\u8bbe\u5b9a\u65f6\u95f4\uff0c\u5c31\u4f1a\u8bb0\u5f55\u5230\u65e5\u5fd7\u4e2d\uff0c\u9ed8\u8ba4\u662f\u6ca1\u6709\u6253\u5f00\u7684\u3002<\/p>\n<p>\u67e5\u770b\u662f\u5426\u5f00\u542f\u6162\u67e5\u8be2\u65e5\u5fd7<br \/>\n\u5f53\u524d\u662f\u5173\u95ed\u7684<\/p>\n<pre><code class=\"language-mysql\">SELECT @@slow_query_log;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708238294598.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 311px; --smush-placeholder-aspect-ratio: 311\/126;\" \/><\/p>\n<p>\u67e5\u770b\u6162\u67e5\u8be2\u65f6\u95f4<br \/>\n\u9ed8\u8ba4\u662f 10s\uff0c\u67e5\u8be2\u65f6\u95f4\u8d85\u8fc7\u5b83\u5c31\u4f1a\u8bb0\u5f55\u65e5\u5fd7<\/p>\n<pre><code class=\"language-mysql\">SELECT @@long_query_time;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708238339695.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 319px; --smush-placeholder-aspect-ratio: 319\/118;\" \/><\/p>\n<p>\u5982\u679c\u8981\u5f00\u542f\u6162\u67e5\u8be2\u65e5\u5fd7\u53ef\u4ee5\u914d\u7f6e\uff1a<\/p>\n<ul>\n<li>Windows\uff1a\u524d\u5f80\u8def\u5f84 <strong>C:\\ProgramData\\MySQL\\MySQL Server \u7248\u672c<\/strong>\uff0c\u7f16\u8f91 <strong>my.ini<\/strong>\uff08\u6253\u5f00\u663e\u793a\u9690\u85cf\u6587\u4ef6\uff0c\u4e0d\u7136\u770b\u4e0d\u5230\u8fd9\u4e2a\u8def\u5f84\uff09<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708234785070.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 987px; --smush-placeholder-aspect-ratio: 987\/584;\" \/><br \/>\n\u8fd9\u4e2a\u6587\u4ef6\u9ed8\u8ba4\u662f\u6ca1\u6709\u7f16\u8f91\u6743\u9650\u7684\uff0c\u53ef\u4ee5\u5728\u8fd9\u4e2a\u6587\u4ef6\u4e0a\u53f3\u952e\u6253\u5f00\u5c5e\u6027<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708237028033.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 423px; --smush-placeholder-aspect-ratio: 423\/648;\" \/><\/li>\n<\/ul>\n<p>\u7ed9\u81ea\u5df1\u7684\u5f53\u524d\u7528\u6237\u6dfb\u52a0\u4fee\u6539\u6743\u9650<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708237070990.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 442px; --smush-placeholder-aspect-ratio: 442\/576;\" \/><\/p>\n<p>\u8fd9\u6837\u5c31\u53ef\u4ee5\u7f16\u8f91\u8fd9\u4e2a\u6587\u4ef6\u4e86\uff0cWindows \u9ed8\u8ba4\u662f\u6253\u5f00\u72b6\u6001\u7684<br \/>\nslow-query-log \u8bbe\u7f6e 1 \u5c31\u662f\u5f00\u542f\uff0c\u8bbe\u7f6e 0 \u5c31\u662f\u5173\u95ed\u3002<br \/>\nslow_query_log_file \u8bbe\u7f6e\u6587\u4ef6\u540d\uff0c\u65e5\u5fd7\u6587\u4ef6\u4f4d\u4e8e <strong>C:\\ProgramData\\MySQL\\MySQL Server \u7248\u672c\\Data<\/strong> \u4e0b\u3002<br \/>\nlong_query_time \u8bbe\u7f6e\u8d85\u65f6\u65f6\u95f4\u3002<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708236812039.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 400px; --smush-placeholder-aspect-ratio: 400\/211;\" \/><\/p>\n<p>\u4fee\u6539\u5b8c\u4fdd\u5b58\uff0c\u5e76\u91cd\u542f MySQL \u670d\u52a1\u5668<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708237507191.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 804px; --smush-placeholder-aspect-ratio: 804\/582;\" \/><\/p>\n<ul>\n<li>Linux\uff1a\u4ee5 root \u6743\u9650\u7f16\u8f91 <strong>\/etc\/my.cnf<\/strong>\uff0c\u6211\u535a\u5ba2\u670d\u52a1\u5668\u7528\u7684 Mariadb 10.3.38 \u4e2d\u8fd9\u4e2a\u6587\u4ef6\u5728 <strong>\/etc\/mysql\/my.cnf<\/strong>\u3002\u914d\u7f6e\u53c2\u6570\u65b9\u6cd5\u540c\u4e0a\u3002<\/li>\n<\/ul>\n<p>\u5982\u679c\u8981\u4e34\u65f6\u8bbe\u7f6e\u53ef\u4ee5\u4f7f\u7528\u4e0b\u9762\u547d\u4ee4\uff08\u91cd\u542f\u6062\u590d\u4e3a\u914d\u7f6e\u6587\u4ef6\u4e2d\u7684\u9ed8\u8ba4\u72b6\u6001\uff09\uff0c\u540e\u7eed\u5176\u5b83\u53d8\u91cf\u4e00\u6837<\/p>\n<pre><code class=\"language-mysql\"># SESSION \u53ea\u5728\u5f53\u524d\u4f1a\u8bdd\u4e2d\uff0cGLOBAL \u5728\u6240\u6709\u5ba2\u6237\u7aef\u90fd\u751f\u6548\nSET [SESSION | GLOBAL] \u53d8\u91cf\u540d = \u53d8\u91cf\u503c\uff1b<\/code><\/pre>\n<hr \/>\n<p>\u5728 Windows \u4e2d\u9ed8\u8ba4\u8bd5\u6253\u5f00\u7684\uff0c\u5728 Linux \u4e2d\u9ed8\u8ba4\u662f\u5173\u95ed\u7684\u3002\u4f30\u8ba1\u56e0\u4e3a\u4e00\u822c\u5f00\u53d1\u662f\u5728 Windows \u4e0a\uff0c\u8fd9\u4e2a\u6253\u5f00\u672c\u6765\u5c31\u662f\u7528\u4e8e\u8c03\u8bd5\uff0c\u800c\u5b9e\u9645\u751f\u4ea7\u73af\u5883\u90e8\u7f72\u4e00\u822c\u662f\u5728 Linux \u4e0a\uff0c\u6240\u4ee5\u9ed8\u8ba4\u662f\u5173\u95ed\u7684\uff0c\u5728\u751f\u4ea7\u73af\u5883\u4e0a\u5f00\u542f\u8fd9\u4e9b\u8bb0\u5f55\u53ea\u4f1a\u589e\u52a0\u8d44\u6e90\u6d88\u8017\uff0c\u6d6a\u8d39\u672c\u8be5\u7528\u4e8e\u4e1a\u52a1\u6267\u884c\u7684\u6027\u80fd\u3002<\/p>\n<h3><span class=\"ez-toc-section\" id=\"profile\"><\/span>profile<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u67e5\u770b\u8bed\u53e5\u6267\u884c\u8017\u65f6<\/p>\n<p>\u67e5\u770b\u662f\u5426\u652f\u6301 profile<\/p>\n<pre><code class=\"language-mysql\">SELECT @@have_profiling;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708239497356.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 204px; --smush-placeholder-aspect-ratio: 204\/57;\" \/><\/p>\n<p>\u67e5\u770b\u6253\u5f00\u72b6\u6001<\/p>\n<pre><code class=\"language-mysql\">SELECT @@profiling;<\/code><\/pre>\n<p>\u4f7f\u7528 SET \u628a\u8fd9\u4e2a\u53d8\u91cf\u6539\u4e3a 1 \u5373\u53ef\u5f00\u542f\uff0c\u5728\u6267\u884c\u8bed\u53e5\u540e\u4f1a\u8bb0\u5f55\u6267\u884c\u65f6\u95f4\uff0c\u901a\u8fc7\u547d\u4ee4\u53ef\u4ee5\u67e5\u8be2<\/p>\n<pre><code class=\"language-mysql\">SHOW PROFILES ;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708240534841.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 486px; --smush-placeholder-aspect-ratio: 486\/607;\" \/><\/p>\n<p>\u67e5\u770b\u6307\u5b9a query_id \u7684\u8bed\u53e5\u7684\u8be6\u7ec6\u8017\u65f6<\/p>\n<pre><code class=\"language-mysql\">SHOW PROFILE FOR QUERY \u67e5\u8be2ID;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708241083943.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 577px; --smush-placeholder-aspect-ratio: 577\/691;\" \/><\/p>\n<p>\u67e5\u770b\u6307\u5b9a query_id \u7684\u8bed\u53e5\u7684 CPU \u4f7f\u7528\u60c5\u51b5<\/p>\n<pre><code class=\"language-mysql\">SHOW PROFILE CPU FOR QUERY \u67e5\u8be2ID;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708241202697.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 648px; --smush-placeholder-aspect-ratio: 648\/445;\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"explain_%E6%89%A7%E8%A1%8C%E8%AE%A1%E5%88%92\"><\/span>explain \u6267\u884c\u8ba1\u5212<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u5728\u6267\u884c\u7684\u8bed\u53e5\u524d\u9762\u52a0\u4e0a <strong>EXPLAIN<\/strong> \u6216 <strong>DESC<\/strong>\uff0c\u67e5\u8be2\u9879\u542b\u4e49\uff1a<\/p>\n<ul>\n<li>id\uff1a\u8868\u67e5\u8be2\u7684\u5e8f\u5217\u53f7\uff0c\u76f8\u540c\u5219\u4ece\u4e0a\u5f80\u4e0b\uff0c\u8d8a\u5927\u7684\u8d8a\u5148\u6267\u884c<\/li>\n<li>select_type\uff1a\u67e5\u8be2\u7c7b\u578b\uff0c\u5e38\u89c1\u7684\u6709 SIMPLE\uff08\u7b80\u5355\u8868\uff0c\u4e0d\u4f7f\u7528\u8868\u8fde\u63a5\u6216\u5b50\u67e5\u8be2\uff09\u3001PRIMARY\uff08\u4e3b\u67e5\u8be2\uff0c\u5373\u5916\u5c42\u7684\u67e5\u8be2\uff09\u3001UNION\uff08UNION \u4e2d\u7684\u7b2c\u4e8c\u4e2a\u6216\u8005\u540e\u9762\u7684\u67e5\u8be2\u8bed\u53e5\uff09\u3001SUBQUERY\uff08\u5305\u542b\u5b50\u67e5\u8be2\uff09\u7b49<\/li>\n<li>type\uff1a\u8fde\u63a5\u7c7b\u578b\uff0c\u6027\u80fd\u4ece\u4f4e\u5230\u9ad8\uff1aNULL\u3001system\u3001const\u3001eq_ref\u3001ref\u3001range\u3001index\u3001all<\/li>\n<li>possible_key\uff1a\u8868\u4e2d\u53ef\u80fd\u7528\u5230\u7684\u7d22\u5f15\u3002<\/li>\n<li>key\uff1a\u5b9e\u9645\u4f7f\u7528\u7684\u7d22\u5f15<\/li>\n<li>key_len\uff1a\u7d22\u5f15\u5b57\u6bb5\u7684\u6700\u5927\u53ef\u80fd\u957f\u5ea6<\/li>\n<li>rows\uff1a\u5fc5\u987b\u8981\u6267\u884c\u67e5\u8be2\u7684\u884c\u6570\uff0c\u5728 InnoDB \u4e2d\u662f\u4e00\u4e2a\u4f30\u8ba1\u503c<\/li>\n<li>filltered\uff1a\u7ed3\u679c\u8fd4\u56de\u7684\u884c\u6570\u5360\u9700\u8981\u8bfb\u53d6\u884c\u6570\u7684\u767e\u5206\u6bd4\uff0c\u8d8a\u5927\u8d8a\u597d\u3002<\/li>\n<\/ul>\n<p>\u91c7\u7528\u8fd9\u91cc\u7684\u4e09\u5f20\u8868\u6765\u6f14\u793a\uff1a<a href=\"https:\/\/blog.iyatt.com\/?p=12631#3_%E5%A4%9A%E5%AF%B9%E5%A4%9A\">https:\/\/blog.iyatt.com\/?p=12631#3_%E5%A4%9A%E5%AF%B9%E5%A4%9A<\/a><\/p>\n<p>\u5185\u8fde\u63a5<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM stu s, course c, stu_course sc WHERE s.id = sc.stu_id AND c.id = sc.course_id \\G;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708261044390.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 960px; --smush-placeholder-aspect-ratio: 960\/818;\" \/><\/p>\n<p>\u5b50\u67e5\u8be2<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM stu s WHERE s.id IN (\n    SELECT stu_id FROM stu_course sc WHERE sc.course_id\n                                     = (SELECT id FROM course c WHERE c.name = '\u9ad8\u6570')\n    ) \\G;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708261410753.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 960px; --smush-placeholder-aspect-ratio: 960\/855;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E4%BD%BF%E7%94%A8\"><\/span>\u4f7f\u7528<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3><span class=\"ez-toc-section\" id=\"%E7%B4%A2%E5%BC%95%E6%9C%89%E6%95%88%E6%9D%A1%E4%BB%B6_%E2%80%93_%E6%9C%80%E5%B7%A6%E5%89%8D%E7%BC%80%E6%B3%95%E5%88%99\"><\/span>\u7d22\u5f15\u6709\u6548\u6761\u4ef6 &#8211; \u6700\u5de6\u524d\u7f00\u6cd5\u5219<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u5982\u679c\u7d22\u5f15\u4e86\u591a\u5217\uff08\u8054\u5408\u7d22\u5f15\uff09\uff0c\u8981\u9075\u5faa\u6700\u5de6\u524d\u7f00\u6cd5\u5219\u3002<\/p>\n<p>\u521b\u5efa\u4e00\u5f20\u8868<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE info (\n                      id tinyint,\n                      age tinyint,\n                      name char(2),\n                      class int\n);<\/code><\/pre>\n<p>\u63d2\u5165\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">INSERT INTO info VALUES\n                     (1, 21, '\u5c0f\u5f3a', 1),\n                     (2, 21, '\u5c0f\u7ea2', 2),\n                     (3, 20, '\u5c0f\u5f20', 1);<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708265494467.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 446px; --smush-placeholder-aspect-ratio: 446\/118;\" \/><\/p>\n<p>\u521b\u5efa\u8054\u5408\u7d22\u5f15\uff08\u540e\u7eed\u63d0\u5230\u7684\u5de6\u53f3\u90fd\u662f\u57fa\u4e8e\u521b\u5efa\u7d22\u5f15\u65f6\u6307\u5b9a\u7684\u5217\u987a\u5e8f\uff09<\/p>\n<pre><code class=\"language-mysql\">CREATE INDEX index_info ON info(age, name, class);<\/code><\/pre>\n<p>\u83b7\u53d6\u6bcf\u4e2a\u5217\u7684 key_len<br \/>\nage name class \u5206\u522b\u4e3a 2 9 5<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708266822523.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 1103px; --smush-placeholder-aspect-ratio: 1103\/734;\" \/><\/p>\n<p>\u540c\u65f6\u6307\u5b9a\u4e09\u5217\u67e5\u8be2<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM info WHERE age = 21 and name = '\u5c0f\u5f3a' and class = 1;<\/code><\/pre>\n<p>\u4f7f\u7528\u4e86\u5168\u90e8\u7d22\u5f15<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708266897916.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 411px; --smush-placeholder-aspect-ratio: 411\/141;\" \/><\/p>\n<p>\u6307\u5b9a\u6700\u5de6\u5217\u548c\u6700\u53f3\u5217\u67e5\u8be2<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM info WHERE age = 21 and class = 1;<\/code><\/pre>\n<p>key_len \u4e3a 2\uff0c\u53ea\u6709\u6700\u5de6\u5217 age \u4f7f\u7528\u7d22\u5f15<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708266921265.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 412px; --smush-placeholder-aspect-ratio: 412\/145;\" \/><\/p>\n<p>\u4e0d\u6307\u5b9a\u6700\u5de6\u4fa7\u5217<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM info WHERE name = '\u5c0f\u5f3a' and class = 1;<\/code><\/pre>\n<p>\u6ca1\u6709\u4f7f\u7528\u7d22\u5f15<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708266960666.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 362px; --smush-placeholder-aspect-ratio: 362\/76;\" \/><\/p>\n<p>age \u5217\u6307\u5b9a\u8303\u56f4<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM info WHERE age > 20 and name = '\u5c0f\u5f3a' and class = 1;<\/code><\/pre>\n<p>key_len \u4e3a 2\uff0c\u4ece age \u5217\u53f3\u4fa7\u4e0b\u4e00\u5217\u5f00\u59cb\u6ca1\u6709\u4f7f\u7528\u7d22\u5f15<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708267141062.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 432px; --smush-placeholder-aspect-ratio: 432\/136;\" \/><\/p>\n<p>\u6253\u4e71\u987a\u5e8f<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM info WHERE class = 1 and name = '\u5c0f\u5f3a' and age = 21;<\/code><\/pre>\n<p>\u987a\u5e8f\u4e0d\u5f71\u54cd\u7d22\u5f15\u4f7f\u7528<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708267212595.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 421px; --smush-placeholder-aspect-ratio: 421\/145;\" \/><\/p>\n<p>\u5373\u8054\u5408\u7d22\u5f15\u5fc5\u987b\u5305\u542b\u6700\u5de6\u5217\u624d\u4f1a\u4f7f\u7528\u7d22\u5f15\uff0c\u4e14\u4e2d\u95f4\u5982\u679c\u6709\u7559\u7a7a\uff0c\u5219\u4ece\u7559\u7a7a\u5217\u5f00\u59cb\u4e0d\u4f7f\u7528\u7d22\u5f15<\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E7%B4%A2%E5%BC%95%E5%A4%B1%E6%95%88%E6%83%85%E5%86%B5_1_%E2%80%93_%E7%B4%A2%E5%BC%95%E5%88%97%E8%BF%90%E7%AE%97\"><\/span>\u7d22\u5f15\u5931\u6548\u60c5\u51b5 1 &#8211; \u7d22\u5f15\u5217\u8fd0\u7b97<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u7528\u4e0a\u9762\u7684\u8868\u6f14\u793a\uff0c\u5728\u8fd9\u4e2a\u8868\u4e2d\u67e5\u8be2\u5e74\u9f84\u4e3a 21\uff0c\u540d\u5b57\u7b2c\u4e8c\u4e2a\u5b57\u4e3a\u201c\u5f3a\u201d\u7684<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM info WHERE age = 21 and substring(name, 2, 1) = '\u5f3a';<\/code><\/pre>\n<p>key_len \u4e3a 2\uff0c\u5373 name \u5b57\u6bb5\u7d22\u5f15\u5931\u6548\u4e86<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708304777429.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 457px; --smush-placeholder-aspect-ratio: 457\/56;\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E7%B4%A2%E5%BC%95%E5%A4%B1%E6%95%88%E6%83%85%E5%86%B5_2_%E2%80%93_%E8%8C%83%E5%9B%B4%E7%B4%A2%E5%BC%95\"><\/span>\u7d22\u5f15\u5931\u6548\u60c5\u51b5 2 &#8211; \u8303\u56f4\u7d22\u5f15<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u4e0a\u9762\u6700\u5de6\u524d\u7f00\u6cd5\u5219\u4e2d\uff0cage \u6307\u5b9a\u8303\u56f4\u6f14\u793a\u8fc7\u3002\u4ece\u8303\u56f4\u7d22\u5f15\u7684\u53f3\u4fa7\u5217\u5f00\u59cb\u7d22\u5f15\u5931\u6548\u3002<\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E7%B4%A2%E5%BC%95%E5%A4%B1%E6%95%88%E6%83%85%E5%86%B5_3_%E2%80%93_%E6%A8%A1%E7%B3%8A%E6%9F%A5%E8%AF%A2\"><\/span>\u7d22\u5f15\u5931\u6548\u60c5\u51b5 3 &#8211; \u6a21\u7cca\u67e5\u8be2<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u7b2c\u4e00\u4e2a\u5b57\u91c7\u7528\u6a21\u7cca\u5339\u914d<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM info WHERE age = 21 AND name LIKE '_\u5f3a';<\/code><\/pre>\n<p>key_len \u4e3a 2\uff0cname \u7d22\u5f15\u5931\u6548<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708312904424.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 449px; --smush-placeholder-aspect-ratio: 449\/65;\" \/><\/p>\n<p>\u975e\u7b2c\u4e00\u4e2a\u5b57\u6a21\u7cca\u5339\u914d<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM info WHERE age = 21 AND name LIKE '\u5c0f_';<\/code><\/pre>\n<p>\u7d22\u5f15\u6b63\u5e38\u5de5\u4f5c<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708312973272.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 469px; --smush-placeholder-aspect-ratio: 469\/65;\" \/><\/p>\n<p>\u7b2c\u4e00\u4e2a\u5b57\u7b26\u6a21\u7cca\u67e5\u8be2\u4f1a\u5bfc\u81f4\u7d22\u5f15\u5931\u6548\uff0c\u975e\u7b2c\u4e00\u4e2a\u5b57\u7b26\u6a21\u7cca\u67e5\u8be2\u7d22\u5f15\u6b63\u5e38\u5de5\u4f5c\u3002<\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E7%B4%A2%E5%BC%95%E5%A4%B1%E6%95%88%E6%83%85%E5%86%B5_4_%E2%80%93_OR_%E8%BF%9E%E6%8E%A5%E7%9A%84%E6%9D%A1%E4%BB%B6\"><\/span>\u7d22\u5f15\u5931\u6548\u60c5\u51b5 4 &#8211; OR \u8fde\u63a5\u7684\u6761\u4ef6<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>OR \u8fde\u63a5\u7684\u6761\u4ef6\uff0c\u4e00\u4e2a\u6709\u7d22\u5f15\uff0c\u4e00\u4e2a\u6ca1\u6709\u7d22\u5f15\uff0c\u90a3\u4e48\u6b64\u65f6\u4e24\u8005\u90fd\u4e0d\u4f1a\u4f7f\u7528\u7d22\u5f15\u3002<\/p>\n<p>\u8fd9\u91cc\u7684 age \u6709\u7d22\u5f15\uff0cid \u6ca1\u6709\u7d22\u5f15<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM info WHERE age = 21 OR id = 1;<\/code><\/pre>\n<p>\u7ed3\u679c\u90fd\u6ca1\u6709\u4f7f\u7528\u7d22\u5f15<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708313864707.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 439px; --smush-placeholder-aspect-ratio: 439\/62;\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E7%B4%A2%E5%BC%95%E5%A4%B1%E6%95%88%E6%83%85%E5%86%B5_5_%E2%80%93_%E6%95%B0%E6%8D%AE%E5%88%86%E5%B8%83%E5%BD%B1%E5%93%8D%EF%BC%88%E4%BC%98%E5%8C%96%EF%BC%89\"><\/span>\u7d22\u5f15\u5931\u6548\u60c5\u51b5 5 &#8211; \u6570\u636e\u5206\u5e03\u5f71\u54cd\uff08\u4f18\u5316\uff09<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u5f53\u4f7f\u7528\u7d22\u5f15\u53ef\u80fd\u66f4\u6162\u7684\u65f6\u5019\uff0cMySQL \u4f1a\u51b3\u5b9a\u4e0d\u4f7f\u7528\u7d22\u5f15\u3002<\/p>\n<p>\u521b\u5efa\u4e00\u5f20\u8868\u7528\u4e8e\u6f14\u793a<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE info1 (\n    id int,\n    name char(2)\n);\n\nINSERT INTO info1 (id, name) VALUES\n                                (1, '\u5f20\u4e09'),\n                                (2, '\u674e\u56db'),\n                                (3, '\u738b\u4e94'),\n                                (4, '\u8d75\u516d'),\n                                (5, '\u5b59\u4e03'),\n                                (6, '\u5468\u516b'),\n                                (7, '\u5434\u4e5d'),\n                                (8, '\u90d1\u5341'),\n                                (9, '\u9648\u4e00'),\n                                (10, '\u6797\u4e8c'),\n                                (11, '\u7f57\u4e09'),\n                                (12, '\u4f55\u56db'),\n                                (13, '\u9ad8\u4e94'),\n                                (14, '\u9a6c\u516d'),\n                                (15, '\u5218\u4e03'),\n                                (16, '\u6881\u516b'),\n                                (17, '\u9ec4\u4e5d'),\n                                (18, '\u66fe\u5341'),\n                                (19, '\u5f6d\u4e00'),\n                                (20, '\u80e1\u4e8c'),\n                                (21, '\u8bb8\u4e09'),\n                                (22, '\u6c88\u56db'),\n                                (23, '\u97e9\u4e94'),\n                                (24, '\u6768\u516d'),\n                                (25, '\u6731\u4e03'),\n                                (26, '\u79e6\u516b'),\n                                (27, '\u5c24\u4e5d'),\n                                (28, '\u8bb8\u5341'),\n                                (29, '\u859b\u4e00'),\n                                (30, '\u4faf\u4e8c'),\n                                (31, '\u590f\u4e09'),\n                                (32, '\u90b1\u56db'),\n                                (33, '\u65b9\u4e94'),\n                                (34, '\u77f3\u516d'),\n                                (35, '\u59da\u4e03'),\n                                (36, '\u8c2d\u516b'),\n                                (37, '\u5ed6\u4e5d'),\n                                (38, '\u8303\u5341'),\n                                (39, '\u6c6a\u4e00'),\n                                (40, '\u9646\u4e8c'),\n                                (41, '\u91d1\u4e09'),\n                                (42, '\u9b4f\u56db'),\n                                (43, '\u9676\u4e94'),\n                                (44, '\u6234\u516d'),\n                                (45, '\u90ed\u4e03'),\n                                (46, '\u6d2a\u516b'),\n                                (47, '\u90b9\u4e5d'),\n                                (48, '\u6c5f\u5341'),\n                                (49, '\u7ae0\u4e00'),\n                                (50, '\u8463\u4e8c');\n\nCREATE INDEX index_info1 ON info1(id);<\/code><\/pre>\n<p>\u67e5\u8be2 id &gt; 10 \u7684\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM info1 WHERE id > 10;<\/code><\/pre>\n<p>\u6ca1\u6709\u4f7f\u7528\u7d22\u5f15<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708316810230.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 478px; --smush-placeholder-aspect-ratio: 478\/76;\" \/><\/p>\n<p>\u67e5\u8be2 id &gt; 30 \u7684\u6570\u636e<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM info1 WHERE id > 30;<\/code><\/pre>\n<p>\u4f7f\u7528\u4e86\u7d22\u5f15<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708316858189.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 482px; --smush-placeholder-aspect-ratio: 482\/72;\" \/><\/p>\n<p>\u5f53\u67e5\u8be2\u7684\u6570\u636e\u662f\u8868\u4e2d\u7684\u5c11\u90e8\u5206\u7684\u65f6\u5019\uff0cMySQL \u4f1a\u4f7f\u7528\u7d22\u5f15\uff0c\u8fd9\u6837\u901f\u5ea6\u66f4\u5feb\uff0c\u4f46\u662f\u67e5\u8be2\u7684\u662f\u8868\u4e2d\u7684\u5927\u90e8\u5206\u6570\u636e\u7684\u65f6\u5019\uff0c\u53ef\u80fd\u4e0d\u5982\u76f4\u63a5\u66b4\u529b\u904d\u5386\u7684\u901f\u5ea6\u3002<\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E7%B4%A2%E5%BC%95%E6%8F%90%E7%A4%BA\"><\/span>\u7d22\u5f15\u63d0\u793a<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u5f53\u4e00\u4e2a\u5217\u5b58\u5728\u591a\u4e2a\u7d22\u5f15\u65f6\uff0c\u53ef\u4ee5\u6307\u5b9a\u4f7f\u7528\u67d0\u4e2a\u7d22\u5f15\u3002<\/p>\n<p>\u8fd9\u91cc\u793a\u4f8b\u8fd8\u662f\u4f7f\u7528\u4e0a\u9762\u521b\u5efa\u7684 info \u8868<br \/>\n\u4e3a age \u5217\u518d\u521b\u5efa\u4e00\u4e2a\u5355\u5217\u7d22\u5f15<\/p>\n<pre><code class=\"language-mysql\">CREATE INDEX index_age ON info(age);<\/code><\/pre>\n<p>\u6b64\u65f6 age \u540c\u65f6\u5177\u6709\u524d\u9762\u7684\u8054\u5408\u7d22\u5f15\uff0c\u53c8\u6709\u4e86\u4e00\u4e2a\u5355\u5217\u7d22\u5f15<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM info WHERE age = 21;<\/code><\/pre>\n<p>\u53ef\u80fd\u7528\u5230\u7684\u7d22\u5f15\u6709\u4e24\u4e2a\uff0c\u5b9e\u9645\u7528\u7684\u662f\u8054\u5408\u7d22\u5f15<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708317686137.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 470px; --smush-placeholder-aspect-ratio: 470\/70;\" \/><\/p>\n<p>\u6307\u5b9a\u4f7f\u7528 index_age \u7d22\u5f15\uff08\u5355\u5217\uff09- \u5efa\u8bae MySQL \u4f7f\u7528\uff0cMySQL \u901a\u8fc7\u4e00\u5b9a\u7b97\u6cd5\u5224\u65ad\u662f\u5426\u4f7f\u7528<br \/>\nUSE INDEX (\u7d22\u5f15\u540d)<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM info USE INDEX (index_age) WHERE age = 21;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708317966497.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 367px; --smush-placeholder-aspect-ratio: 367\/71;\" \/><\/p>\n<p>\u5ffd\u7565\u7d22\u5f15 index_info\uff08\u8054\u5408\uff09<br \/>\nIGNORE INDEX (\u7d22\u5f15\u540d)<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM info IGNORE INDEX (index_info) WHERE age = 21;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708318061270.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 477px; --smush-placeholder-aspect-ratio: 477\/75;\" \/><\/p>\n<p>\u5f3a\u5236\u4f7f\u7528\u7d22\u5f15 index_age\uff08\u5355\u5217\uff09<br \/>\nFORCE INDEX (\u7d22\u5f15\u540d)<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM info FORCE INDEX (index_age) WHERE age = 21;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708318136162.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 380px; --smush-placeholder-aspect-ratio: 380\/81;\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E8%A6%86%E7%9B%96%E7%B4%A2%E5%BC%95\"><\/span>\u8986\u76d6\u7d22\u5f15<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u67e5\u8be2\u7684\u5217\u6570\u636e\u90fd\u5305\u542b\u5728\u7d22\u5f15\u4e2d<\/p>\n<p>\u4f7f\u7528\u4e0a\u9762\u7684 info \u8868\uff0c\u5220\u6389\u521b\u5efa\u7684\u7d22\u5f15\uff0c\u53ea\u4fdd\u7559\u539f\u5148\u7684\u8054\u5408\u7d22\u5f15<\/p>\n<p>\u5f53\u67e5\u8be2\u9879\u90fd\u5728\u7d22\u5f15\u4e2d\u65f6<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT age, name, class FROM info WHERE age = 21 AND name = '\u5c0f\u5f3a' AND class = 1;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708324695986.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 248px; --smush-placeholder-aspect-ratio: 248\/78;\" \/><\/p>\n<p>\u5f53\u67e5\u8be2\u9879\u591a\u4e86\u4e00\u4e2a id\uff08\u4e0d\u5728\u7d22\u5f15\u4e2d\uff09<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT id, age, name, class FROM info WHERE age = 21 AND name = '\u5c0f\u5f3a' AND class = 1;<\/code><\/pre>\n<p>\u6216\u8005\u67e5 *<\/p>\n<pre><code class=\"language-mysql\">EXPLAIN SELECT * FROM info WHERE age = 21 AND name = '\u5c0f\u5f3a' AND class = 1;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708324935938.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 211px; --smush-placeholder-aspect-ratio: 211\/71;\" \/><\/p>\n<ul>\n<li>Using index condition\uff1a\u8868\u793a\u4f7f\u7528\u4e86\u7d22\u5f15\u6761\u4ef6\u4e0b\u63a8\uff08Index Condition Pushdown\uff0cICP\uff09\u7684\u4f18\u5316\uff0c\u5373\u5728\u5b58\u50a8\u5f15\u64ce\u5c42\u5bf9\u7d22\u5f15\u8fdb\u884c\u8fc7\u6ee4\uff0c\u51cf\u5c11\u56de\u8868\u67e5\u8be2\u7684\u6b21\u6570\u3002<\/li>\n<li>Using where\uff1a\u8868\u793a\u5728\u670d\u52a1\u5668\u5c42\u5bf9\u6570\u636e\u8fdb\u884c\u8fc7\u6ee4\uff0c\u901a\u5e38\u662f\u56e0\u4e3a\u7d22\u5f15\u4e0d\u80fd\u5b8c\u5168\u6ee1\u8db3\u67e5\u8be2\u6761\u4ef6\uff0c\u6216\u8005\u6ca1\u6709\u4f7f\u7528\u7d22\u5f15\u3002<\/li>\n<li>Using index\uff1a\u8868\u793a\u4f7f\u7528\u4e86\u8986\u76d6\u7d22\u5f15\uff08Covering Index\uff09\u7684\u4f18\u5316\uff0c\u5373\u7d22\u5f15\u5df2\u7ecf\u5305\u542b\u4e86\u6240\u9700\u7684\u6240\u6709\u5217\uff0c\u65e0\u9700\u8bbf\u95ee\u6570\u636e\u8868<\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"%E5%89%8D%E7%BC%80%E7%B4%A2%E5%BC%95\"><\/span>\u524d\u7f00\u7d22\u5f15<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u5f53\u5b57\u6bb5\u7c7b\u578b\u4e3a\u5b57\u7b26\u4e32\u65f6\uff0c\u6709\u65f6\u5019\u9700\u8981\u7d22\u5f15\u5f88\u957f\u7684\u5b57\u7b26\u4e32\uff0c\u4f46\u662f\u8fd9\u6837\u4f1a\u8ba9\u7d22\u5f15\u53d8\u5f97\u5f88\u5927\uff0c\u67e5\u8be2\u7684\u65f6\u5019\u78c1\u76d8 IO \u5360\u7528\u4f1a\u975e\u5e38\u9ad8\uff0c\u5f71\u54cd\u67e5\u8be2\u6548\u7387\u3002\u56e0\u6b64\u53ef\u4ee5\u53ea\u5c06\u5b57\u7b26\u4e32\u7684\u4e00\u90e8\u5206\u524d\u7f00\u5efa\u7acb\u7d22\u5f15\uff0c\u8fd9\u6837\u53ef\u4ee5\u63d0\u9ad8\u7d22\u5f15\u6548\u7387\u3002<\/p>\n<pre><code class=\"language-mysql\">CREATE INDEX \u7d22\u5f15\u540d ON \u8868\u540d(\u5217\u540d(\u524dn\u4e2a\u5b57\u7b26))<\/code><\/pre>\n<p>\u81f3\u4e8e\u8fd9\u524dn\u4e2a\u5b57\u7b26\u5177\u4f53\u53d6\u591a\u5c11\u4e2a\uff0c\u53ef\u4ee5\u53c2\u8003\u201c\u7d22\u5f15\u7684\u9009\u62e9\u6027\u201d\u3002\u6bd4\u5982\u67d0\u5217\u7684\u5b57\u6bb5\u5185\u5bb9\u8f83\u957f\uff0c\u8003\u8651\u5efa\u7acb\u524d\u7f00\u7d22\u5f15\uff0c\u6240\u5728\u7684\u8868\u4e2d\u6709100\u884c\u6570\u636e\uff0c\u5982\u679c\u6bcf\u884c\u7684\u8be5\u5b57\u6bb5\u90fd\u53ea\u53d6\u524d 10 \u4e2a\u5b57\u7b26\uff0c\u7ed3\u679c\u8fd9 100 \u884c\u90fd\u6ca1\u6709\u91cd\u590d\uff0c\u90a3\u4e48\u9009\u62e9\u6027 = \u6ca1\u6709\u91cd\u590d\u7684\u884c\u6570 100 \/ \u603b\u884c\u6570 100 = 1\u3002\u7136\u540e\u53c8\u5c1d\u8bd5\u5f80\u524d\u63a8\u8fdb\u770b\u770b\uff0c\u8be5\u5b57\u6bb5\u53d6\u524d 9 \u4e2a\u5b57\u7b26\uff0c\u7ed3\u679c\u6709 10 \u884c\u548c\u5df2\u7ecf\u5b58\u5728\u7684\u91cd\u590d\uff0c\u90a3\u4e48\u9009\u62e9\u6027= \u53bb\u9664\u91cd\u590d\u7684\u884c\u6570 (100-10) \/ \u603b\u884c\u6570 100 = 0.9\u3002\u524d\u4e00\u79cd\u524d\u7f00\u53d6 10\uff0c\u6bcf\u884c\u90fd\u662f\u72ec\u4e00\u65e0\u4e8c\u7684\uff0c\u8fd9\u79cd\u60c5\u51b5\u4e0b\u7d22\u5f15\u901f\u5ea6\u5fc5\u7136\u597d\uff0c\u540e\u4e00\u79cd\u60c5\u51b5\u524d\u7f00\u53d6 9\uff0c\u4f46\u662f\u53ea\u6709 0.9 \u7684\u6bd4\u4f8b\u4e3a\u975e\u91cd\u590d\uff0c\u4f1a\u5f71\u54cd\u4e00\u5b9a\u6548\u7387\uff08\u9047\u5230\u91cd\u590d\u7b49\u4e8e\u7d22\u5f15\u5931\u6548\uff0c\u8981\u56de\u8868\u67e5\u8be2\uff09\uff0c\u4f46\u662f\u7d22\u5f15\u80fd\u8282\u7701\u4e00\u4e2a\u5b57\u7b26\u7684\u7a7a\u95f4\u3002\u7d22\u5f15\u7684\u9009\u62e9\u6027\u5c31\u662f\u4e00\u79cd\u4f5c\u4e3a\u53c2\u8003\u7684\u53c2\u6570\uff0c\u6765\u8f85\u52a9\u9009\u62e9\u524d\u7f00\u5927\u5c0f\uff0c\u7efc\u5408\u524d\u7f00\u957f\u5ea6\u51cf\u5c0f\u53c8\u80fd\u4fdd\u8bc1\u8f83\u597d\u7684\u9009\u62e9\u6027\u6570\u503c\u3002<\/p>\n<p>\u4e0b\u9762\u662f\u4e00\u4e2a\u793a\u4f8b\u8868\uff0c\u521b\u5efa\u5b83<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE info2 (\n    name char(2),\n    email varchar(32)\n);\n\nINSERT INTO info2 VALUES\n                      ('\u5c0f\u5f3a', '123456789@qq.com'),\n                      ('\u5c0f\u738b', '123459875@foxmail.com'),\n                      ('\u5c0f\u674e', 'xiaoli@baidu.com'),\n                      ('\u5c0f\u7ea2', '1234567@douyin.com'),\n                      ('\u5c0f\u5f20', '123986@360.com'),\n                      ('\u5c0f\u8c22', 'xioaoxie@a.com'),\n                      ('\u5c0f\u9648', 'xiaochen@b.cn'),\n                      ('\u5c0f\u6768', 'xiaoyang@c.cpn'),\n                      ('\u5c0f\u8d75', 'xiaozhao@d.com'),\n                      ('\u5c0f\u5510', '1234587@t.com');<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708501870865.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 358px; --smush-placeholder-aspect-ratio: 358\/289;\" \/><\/p>\n<pre><code class=\"language-mysql\">SELECT count(DISTINCT substring(email, 1, \u524d\u7f00\u957f\u5ea6)) \/ count(*) FROM info2;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708503734130.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 720px; --smush-placeholder-aspect-ratio: 720\/601;\" \/><\/p>\n<p>\u524d\u7f00\u53d6 8 \u7684\u65f6\u5019\u9009\u62e9\u6027\u4e3a 1\uff0c\u524d\u7f00\u53d6\u5230 7\u30016 \u90fd\u662f 0.9\uff0c\u53d6\u5230 5 \u5c31\u53ea\u6709 0.7 \u4e86\uff0c\u90a3\u6211\u5c31\u53d6 6<\/p>\n<pre><code class=\"language-mysql\">CREATE INDEX prefix_index_email ON info2(email(6));<\/code><\/pre>\n<p>\u67e5\u770b\u7d22\u5f15\u65f6\uff0c\u5176\u4e2d Sub_part \u5b57\u6bb5\u4e3a 6\uff0c\u975e\u524d\u7f00\u7d22\u5f15\u8fd9\u4e2a\u503c\u5c31\u662f NULL<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708504188541.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 614px; --smush-placeholder-aspect-ratio: 614\/378;\" \/><\/p>\n<p>\u7b2c\u4e00\u4e2a rows \u4e3a 1\uff0c\u7b2c\u4e8c\u4e2a\u4e3a 2\u3002\u56e0\u4e3a\u7b2c\u4e00\u4e2a\u5728\u524d\u7f00\u7d22\u5f15\u53d6 6 \u65f6\u6ca1\u6709\u91cd\u590d\u7684\u7d22\u5f15\uff0c\u800c\u540e\u4e00\u4e2a\u7d22\u5f15\u6709\u91cd\u590d\u7684\uff0c\u90a3\u4e48\u5c31\u9700\u8981\u56de\u5230\u6570\u636e\u8868\u4e2d\u53bb\u786e\u8ba4\u662f\u5426\u91cd\u590d\uff0c\u4e5f\u5c31\u8fd8\u9700\u8981\u989d\u5916\u67e5\u4e00\u6b21\u3002<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708504338253.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 742px; --smush-placeholder-aspect-ratio: 742\/316;\" \/><\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708505180063.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 768px; --smush-placeholder-aspect-ratio: 768\/310;\" \/><\/p>\n<h1><span class=\"ez-toc-section\" id=\"%E5%85%B6%E5%AE%83%E4%BC%98%E5%8C%96\"><\/span>\u5176\u5b83\u4f18\u5316<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<h2><span class=\"ez-toc-section\" id=\"%E6%8F%92%E5%85%A5%E4%BC%98%E5%8C%96\"><\/span>\u63d2\u5165\u4f18\u5316<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<ul>\n<li>\u591a\u6761\u6570\u636e\uff0cINSERT \u6700\u597d\u4e00\u6b21\u6027\u63d2\u5165\u591a\u6761\u6570\u636e\uff0c\u800c\u4e0d\u662f\u6bcf\u6b21\u4e00\u6761\u3002<\/li>\n<li>\u5f53\u6570\u636e\u91cf\u8fc7\u4e8e\u592a\u5927\u65f6\uff0c\u4e5f\u4e0d\u8981\u4e00\u6b21\u6027\u63d2\u5165\uff0c\u53ef\u4ee5\u4e00\u6b21\u6027\u63d2\u5165 500-1000 \u6761<\/li>\n<li>\u8fde\u7eed\u6267\u884c INSERT \u65f6\u6700\u597d\u663e\u5f0f\u5f00\u542f\u4e8b\u52a1\uff0c\u6267\u884c\u5b8c\u6240\u6709\u63d2\u5165\u540e\u4e00\u6b21\u6027\u63d0\u4ea4<\/li>\n<\/ul>\n<hr \/>\n<h3><span class=\"ez-toc-section\" id=\"%E4%BB%8E%E6%96%87%E4%BB%B6%E5%AF%BC%E5%85%A5%E6%95%B0%E6%8D%AE\"><\/span>\u4ece\u6587\u4ef6\u5bfc\u5165\u6570\u636e<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u8fd9\u91cc\u5199\u4e86\u4e00\u4e2a Python \u811a\u672c\u7528\u6765\u751f\u6210 csv \u6570\u636e<\/p>\n<pre><code class=\"language-py\">import random\n\ndef write_to_file(filename, delimiter, newline, rows):\n    with open(filename, 'w', encoding='utf-8') as f:\n        for i in range(rows):\n            id = i + 1\n            line = str(id) + delimiter + ''.join(random.sample('abcdefghijklmnopqrstuvwxyz', 12)) + delimiter + str(random.randint(0,1)) + delimiter + str(random.randint(0, 100))\n            f.write(line + newline)\n\n# \u751f\u6210\u6587\u4ef6\u540d test.csv\n# \u5206\u9694\u7b26\u4e3a\u82f1\u6587\u9017\u53f7\n# \u6362\u884c\u7b26\u4e3a \\r\n# \u6570\u636e\u884c\u6570 1000000\nwrite_to_file('test.csv', ',', '\\r', 1000000)<\/code><\/pre>\n<p>\u8fd9\u91cc\u8fde\u63a5\u6570\u636e\u5e93\u7684\u547d\u4ee4\u8981\u52a0\u4e0a\u989d\u5916\u53c2\u6570<\/p>\n<pre><code class=\"language-mysql\">mysql --local-infile -u root -p<\/code><\/pre>\n<p>\u542f\u7528\u6587\u4ef6\u5bfc\u5165<\/p>\n<pre><code class=\"language-mysql\">SET GLOBAL local_infile = 1;<\/code><\/pre>\n<p>\u7136\u540e\u521b\u5efa\u4e00\u5f20\u548c\u6570\u636e\u5217\u5339\u914d\u7684\u8868\uff0c\u6bd4\u5982\u5339\u914d\u8fd9\u91cc\u7684\u4f8b\u5b50\u7684\u8868<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE person (\n    id int PRIMARY KEY COMMENT '\u552f\u4e00\u6807\u8bc6',\n    name char(12) COMMENT '\u540d\u5b57',\n    gender tinyint COMMENT '\u6027\u522b',\n    age tinyint COMMENT '\u5e74\u9f84'\n);<\/code><\/pre>\n<p>\u5bfc\u5165\u6587\u4ef6<\/p>\n<pre><code class=\"language-mysql\">LOAD DATA LOCAL INFILE \u6587\u4ef6\u8def\u5f84 INTO TABLE \u8868\u540d FIELDS TERMINATED BY \u5206\u9694\u7b26 LINES TERMINATED BY \u6362\u884c\u7b26;<\/code><\/pre>\n<p>\u5bfc\u5165\u4e00\u767e\u4e07\u884c\u6570\u636e\u7528\u4e86 22.96s<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708603815740.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 1007px; --smush-placeholder-aspect-ratio: 1007\/78;\" \/><\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708603989952.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 543px; --smush-placeholder-aspect-ratio: 543\/508;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E4%B8%BB%E9%94%AE%E4%BC%98%E5%8C%96\"><\/span>\u4e3b\u952e\u4f18\u5316<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<ul>\n<li>\u63d2\u5165\u7684\u6570\u636e\u4f1a\u6309\u7167\u4e3b\u952e\u987a\u5e8f\u50a8\u5b58\uff0c\u6700\u597d\u662f\u6309\u7167\u4e3b\u952e\u987a\u5e8f\u63d2\u5165\uff0c\u8fd9\u6837\u6bcf\u6b21\u63d2\u5165\u90fd\u662f\u63a5\u7740\u524d\u4e00\u4e2a\u7684\u540e\u9762\u987a\u5e8f\u63d2\u5165\uff0c\u4e71\u5e8f\u63d2\u5165\u65f6\u9700\u8981\u79fb\u52a8\u6570\u636e\u6765\u4fdd\u6301\u4e3b\u952e\u987a\u5e8f\u5f71\u54cd\u6548\u7387\uff08\u9875\u5206\u88c2\uff09\u3002\u521b\u5efa\u8868\u7684\u65f6\u5019\u6700\u597d\u4f7f\u7528\u81ea\u589e\u4e3b\u952e\uff0c\u4e1a\u52a1\u64cd\u4f5c\u7684\u65f6\u5019\u5c3d\u91cf\u4e0d\u8981\u4fee\u6539\u4e3b\u952e\u3002<\/li>\n<li>\u5c3d\u91cf\u964d\u4f4e\u4e3b\u952e\u7684\u957f\u5ea6<\/li>\n<\/ul>\n<h2><span class=\"ez-toc-section\" id=\"%E6%8E%92%E5%BA%8F%E4%BC%98%E5%8C%96\"><\/span>\u6392\u5e8f\u4f18\u5316<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u4f7f\u7528\u524d\u9762\u7684 100 \u4e07\u884c\u6570\u636e\u7684\u4f8b\u5b50\uff0c\u6309\u7167\u5e74\u9f84\u6392\u5e8f\uff0c\u5e76\u8f93\u51fa\u524d 1000 \u884c<\/p>\n<pre><code class=\"language-mysql\">SELECT * FROM person ORDER BY age LIMIT 1000;<\/code><\/pre>\n<p>\u7528\u65f6 0.69s<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708669630603.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 290px; --smush-placeholder-aspect-ratio: 290\/72;\" \/><\/p>\n<p>\u518d\u4e3a\u5e74\u9f84\u521b\u5efa\u4e00\u4e2a\u7d22\u5f15\uff08\u56e0\u4e3a\u6570\u636e\u91cf\u5927\uff0c\u521b\u5efa\u8fc7\u7a0b\u53ef\u80fd\u6bd4\u8f83\u8017\u65f6\uff09<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708669713301.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 448px; --smush-placeholder-aspect-ratio: 448\/88;\" \/><\/p>\n<p>\u518d\u6b21\u6309\u5e74\u9f84\u6392\u5e8f\u67e5\u8be2\uff0c\u8017\u65f6\u53ef\u4ee5\u5ffd\u7565\u4e0d\u8bb0<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708669746022.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 318px; --smush-placeholder-aspect-ratio: 318\/81;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E5%88%86%E7%BB%84%E4%BC%98%E5%8C%96\"><\/span>\u5206\u7ec4\u4f18\u5316<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u4e0a\u9762\u521b\u5efa\u4e86 age \u7684\u7d22\u5f15\uff0c\u73b0\u5728\u6839\u636e age \u5206\u7c7b\u7edf\u8ba1\u6bcf\u4e2a\u5e74\u9f84\u7684\u4eba\u6570<\/p>\n<pre><code class=\"language-mysql\">SELECT age, COUNT(*) FROM person GROUP BY age;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708672975232.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 283px; --smush-placeholder-aspect-ratio: 283\/68;\" \/><\/p>\n<p>\u7136\u540e\u5220\u6389 age \u7684\u7d22\u5f15\uff0c\u518d\u6b21\u6267\u884c\uff0c\u8017\u65f6\u5dee\u4e0d\u591a\u7ffb\u500d<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708673157087.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 391px; --smush-placeholder-aspect-ratio: 391\/86;\" \/><\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708673179222.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 301px; --smush-placeholder-aspect-ratio: 301\/60;\" \/><\/p>\n<h1><span class=\"ez-toc-section\" id=\"%E8%A7%86%E5%9B%BE\"><\/span>\u89c6\u56fe<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>\u73b0\u6709\u6570\u636e\u5e93\u4e2d\u7684\u8868\u67e5\u8be2\u7ed3\u679c\u521b\u5efa\u51fa\u4e00\u5f20\u65b0\u7684\u8868\uff08\u865a\u62df\u8868\uff09\uff0c\u8fd9\u5f20\u65b0\u7684\u8868\u5c31\u662f\u89c6\u56fe\uff0c\u89c6\u56fe\u53ef\u4ee5\u770b\u4f5c\u662f\u4e00\u4e2a\u5feb\u6377\u65b9\u5f0f\uff0c\u521b\u5efa\u7684\u65f6\u5019\u7ed9\u6307\u5b9a\u8bed\u53e5\u6574\u4f53\u8d77\u4e2a\u522b\u540d\uff0c\u540e\u7eed\u4f7f\u7528\u522b\u540d\u67e5\u8be2\u5c31\u662f\u5728\u521b\u5efa\u8bed\u53e5\u7684\u57fa\u7840\u4e0a\u64cd\u4f5c\uff0c\u521b\u5efa\u89c6\u56fe\u5e76\u4e0d\u989d\u5916\u5b58\u50a8\u8868\uff0c\u90fd\u662f\u91cd\u65b0\u6267\u884c\u8bed\u53e5\u53bb\u67e5\u8be2\u3002<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E5%9F%BA%E6%9C%AC%E4%BD%BF%E7%94%A8\"><\/span>\u57fa\u672c\u4f7f\u7528<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u521b\u5efa\u89c6\u56fe<\/p>\n<pre><code class=\"language-mysql\">CREATE VIEW \u89c6\u56fe\u540d AS SELECT\u8bed\u53e5;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708696656352.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 892px; --smush-placeholder-aspect-ratio: 892\/75;\" \/><\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708696693629.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 353px; --smush-placeholder-aspect-ratio: 353\/406;\" \/><\/p>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708696703706.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 409px; --smush-placeholder-aspect-ratio: 409\/507;\" \/><\/p>\n<p>\u67e5\u8be2\u521b\u5efa\u8bed\u53e5<\/p>\n<pre><code class=\"language-mysql\">SHOW CREATE VIEW \u89c6\u56fe\u540d;<\/code><\/pre>\n<p>\u67e5\u8be2\u89c6\u56fe<\/p>\n<pre><code class=\"language-mysql\">SELECT * FROM \u89c6\u56fe\u540d;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708696800768.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 393px; --smush-placeholder-aspect-ratio: 393\/407;\" \/><\/p>\n<p>\u4fee\u6539\u89c6\u56fe\u65b9\u5f0f\u4e00<\/p>\n<pre><code class=\"language-mysql\">CREATE OR REPLACE VIEW \u89c6\u56fe\u540d AS SELECT\u8bed\u53e5;<\/code><\/pre>\n<p>\u4fee\u6539\u89c6\u56fe\u65b9\u5f0f\u4e8c<\/p>\n<pre><code class=\"language-mysql\">ALTER VIEW \u89c6\u56fe\u540d AS SELECT\u8bed\u53e5;<\/code><\/pre>\n<p>\u5220\u9664\u89c6\u56fe<\/p>\n<pre><code class=\"language-mysql\">DROP VIEW \u89c6\u56fe\u540d;<\/code><\/pre>\n<h2><span class=\"ez-toc-section\" id=\"%E6%A3%80%E6%9F%A5%E9%80%89%E9%A1%B9\"><\/span>\u68c0\u67e5\u9009\u9879<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u521b\u5efa\u89c6\u56fe\u7684\u65f6\u5019\u5728\u540e\u9762\u52a0\u4e0a\u68c0\u67e5\u9009\u9879\uff0c\u5f53\u67e5\u8be2\u8bed\u53e5\u5b58\u5728\u4e00\u5b9a\u7684 WHERE \u6761\u4ef6\uff0c\u800c\u5c1d\u8bd5\u5bf9\u89c6\u56fe\u63d2\u5165\u7684\u6570\u636e\u4e0d\u6ee1\u8db3 WHERE \u6761\u4ef6\u65f6\u4f1a\u963b\u6b62\u63d2\u5165\u3002<\/p>\n<pre><code class=\"language-mysql\">CREATE VIEW \u89c6\u56fe\u540d AS SELECT\u8bed\u53e5 WITH [ CASCADED | LOCAL ] CHECK OPTION ;<\/code><\/pre>\n<p>\u4e0d\u6307\u5b9a CASCADED \u6216 LOCAL\uff0c\u9ed8\u8ba4\u5c31\u662f CASCADED\u3002\u57fa\u4e8e\u8868\u521b\u5efa\u89c6\u56fe\u7684\u65f6\u5019\uff0c\u4e24\u4e2a\u6ca1\u6709\u533a\u522b\uff0c\u90fd\u4f1a\u5bf9\u5f53\u524d\u89c6\u56fe\u7684\u521b\u5efa\u8bed\u53e5\u7684 WHERE \u6761\u4ef6\u68c0\u67e5\u3002\u533a\u522b\u5728\u4e8e\u57fa\u4e8e\u89c6\u56fe\u521b\u5efa\u89c6\u56fe\u7684\u65f6\u5019\uff0cLOCAL \u53ea\u68c0\u67e5\u5f53\u524d\u89c6\u56fe\u7684\u521b\u5efa\u8bed\u53e5\uff0c\u800c\u5bf9\u4e8e\u5b83\u7684\u6240\u6709\u4e0a\u7ea7\u89c6\u56fe\u7684\u6761\u4ef6\u4e0d\u7ba1\uff0c\u800c CASCADED \u5219\u662f\u5bf9\u6240\u6709\u7684\u4e0a\u7ea7\u89c6\u56fe\u8d77\u4f5c\u7528\u3002<\/p>\n<p>\u521b\u5efa\u4e00\u5f20\u8868\u8fdb\u884c\u6d4b\u8bd5<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE test (\n    id int PRIMARY KEY AUTO_INCREMENT,\n    num int\n);<\/code><\/pre>\n<p>LOCAL \u6d4b\u8bd5\uff0c\u521b\u5efa\u56db\u4e2a\u89c6\u56fe<\/p>\n<pre><code class=\"language-mysql\">CREATE OR REPLACE VIEW test_view1 AS SELECT * FROM test;\nCREATE OR REPLACE VIEW test_view2 AS SELECT * FROM test_view1 WHERE num > 0 WITH LOCAL CHECK OPTION ;\nCREATE OR REPLACE VIEW test_view3 AS SELECT * FROM test_view2 WHERE num > 5;\nCREATE OR REPLACE VIEW test_view4 AS SELECT * FROM test_view3 WHERE num < 10 WITH LOCAL CHECK OPTION ;<\/code><\/pre>\n<p>\u63d2\u5165 -1 \u4e0d\u6ee1\u8db3 test_view2 \u7684\u6761\u4ef6<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708763666641.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 602px; --smush-placeholder-aspect-ratio: 602\/93;\" \/><\/p>\n<p>\u63d2\u5165 2 \u6210\u529f\uff0c\u6ee1\u8db3 test_view2 \u548c test_view4 \u7684\u6761\u4ef6\uff0c\u867d\u7136\u4e0d\u6ee1\u8db3 test_view3 \u7684\u6761\u4ef6\uff0c\u4f46\u662f test_view3 \u6ca1\u6709\u68c0\u67e5\u9009\u9879\u4e0d\u53d7\u5f71\u54cd<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708763718830.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 469px; --smush-placeholder-aspect-ratio: 469\/71;\" \/><\/p>\n<p>CASCADED \u6d4b\u8bd5\uff0c\u91cd\u65b0\u521b\u5efa\u89c6\u56fe<\/p>\n<pre><code class=\"language-mysql\">CREATE OR REPLACE VIEW test_view1 AS SELECT * FROM test;\nCREATE OR REPLACE VIEW test_view2 AS SELECT * FROM test_view1 WHERE num > 0;\nCREATE OR REPLACE VIEW test_view3 AS SELECT * FROM test_view2 WHERE num > 5;\nCREATE OR REPLACE VIEW test_view4 AS SELECT * FROM test_view3 WHERE num < 10 WITH CASCADED CHECK OPTION ;<\/code><\/pre>\n<p>\u518d\u6b21\u5c1d\u8bd5\u63d2\u5165 -1 \u548c 2 \u90fd\u5931\u8d25\u4e86\uff0c\u6b64\u65f6 test_view4 \u7684\u68c0\u67e5\u6761\u4ef6\u4e3a CASCADED\uff0c\u867d\u7136\u5f80\u4e0a\u90fd\u6ca1\u6709\u68c0\u67e5\u9009\u9879\uff0c\u4f46\u662f CASCADED \u5f80\u4e0a\u9012\u5f52\uff0c\u5168\u90fd\u4f1a\u68c0\u67e5\uff0c\u63d2\u5165 7 \u7684\u65f6\u5019\u6210\u529f\u4e86\uff0c\u5b83\u6ee1\u8db3\u6240\u6709\u89c6\u56fe\u7684\u6761\u4ef6\u3002<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708763904725.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 618px; --smush-placeholder-aspect-ratio: 618\/136;\" \/><\/p>\n<h1><span class=\"ez-toc-section\" id=\"%E5%AD%98%E5%82%A8%E8%BF%87%E7%A8%8B\"><\/span>\u5b58\u50a8\u8fc7\u7a0b<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>\u201c\u50a8\u5b58\u8fc7\u7a0b\u201d\u7684\u4f5c\u7528\u6709\u70b9\u50cf\u4e00\u822c\u7f16\u7a0b\u8bed\u8a00\u91cc\u7684\u51fd\u6570\uff0c\u628a\u4e00\u5806\u529f\u80fd\u8bed\u53e5\u5c01\u88c5\u8d77\u6765\u8c03\u7528\u3002<\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E8%AF%AD%E5%8F%A5%E5%88%86%E9%9A%94%E7%AC%A6%E4%BF%AE%E6%94%B9\"><\/span>\u8bed\u53e5\u5206\u9694\u7b26\u4fee\u6539<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>MySQL \u9ed8\u8ba4\u7684\u8bed\u53e5\u5206\u9694\u7b26\u662f\u82f1\u6587\u5206\u53f7 <strong>;<\/strong><br \/>\n\u5728 MySQL \u5ba2\u6237\u7aef\u4e2d\u521b\u5efa\u5b58\u50a8\u8fc7\u7a0b\u65f6\uff0c\u8fd8\u662f\u7528\u5206\u53f7\u4f5c\u4e3a\u5206\u9694\u7b26\u7684\u8bdd\u4f1a\u5bfc\u81f4\u65e0\u6cd5\u6b63\u5e38\u8bc6\u522b\u8bed\u53e5\uff0c\u6240\u4ee5\u9700\u8981\u4fee\u6539\uff08\u53ea\u5728\u5f53\u524d\u4f1a\u8bdd\u751f\u6548\uff09<\/p>\n<pre><code class=\"language-mysql\">DELIMITER \u65b0\u7684\u5206\u9694\u7b26<\/code><\/pre>\n<h2><span class=\"ez-toc-section\" id=\"%E5%9F%BA%E6%9C%AC%E4%BD%BF%E7%94%A8-2\"><\/span>\u57fa\u672c\u4f7f\u7528<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u521b\u5efa\u5b58\u50a8\u8fc7\u7a0b<\/p>\n<pre><code class=\"language-mysql\">DELIMITER $$ # \u4fee\u6539\u5206\u9694\u7b26\nCREATE PROCEDURE \u5b58\u50a8\u8fc7\u7a0b\u540d\u5b57()\nBEGIN\n    \u6267\u884c\u7684\u64cd\u4f5c\nEND $$\nDELIMITER ; # \u5207\u6362\u56de\u5206\u53f7<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708770721935.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 380px; --smush-placeholder-aspect-ratio: 380\/132;\" \/><\/p>\n<p>\u8c03\u7528\u81ea\u5b9a\u4e49\u7684\u5b58\u50a8\u8fc7\u7a0b<\/p>\n<pre><code class=\"language-mysql\">CALL \u5b58\u50a8\u8fc7\u7a0b\u540d\u5b57();<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708770809855.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 304px; --smush-placeholder-aspect-ratio: 304\/182;\" \/><\/p>\n<p>\u67e5\u770b\u5b58\u50a8\u8fc7\u7a0b\u5b9a\u4e49<\/p>\n<pre><code class=\"language-mysql\">SHOW CREATE PROCEDURE \u5b58\u50a8\u8fc7\u7a0b\u540d\u5b57;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708770912069.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 1100px; --smush-placeholder-aspect-ratio: 1100\/255;\" \/><\/p>\n<p>\u5220\u9664\u5b58\u50a8\u8fc7\u7a0b<\/p>\n<pre><code class=\"language-mysql\">DROP PROCEDURE \u5b58\u50a8\u8fc7\u7a0b\u540d\u5b57;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708771260627.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 356px; --smush-placeholder-aspect-ratio: 356\/63;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E5%8F%98%E9%87%8F\"><\/span>\u53d8\u91cf<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3><span class=\"ez-toc-section\" id=\"%E7%B3%BB%E7%BB%9F%E5%8F%98%E9%87%8F\"><\/span>\u7cfb\u7edf\u53d8\u91cf<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u7531 MySQL \u5b9a\u4e49\u7684\u5177\u6709\u7279\u6b8a\u542b\u4e49\u7684\u53d8\u91cf\uff0c\u6709\u5168\u5c40 GLOBAL \u548c SESSION \u4e24\u7c7b\uff0c\u524d\u8005\u9488\u5bf9\u6574\u4e2a\u6570\u636e\u5e93\u7cfb\u7edf\u751f\u6548\uff0c\u540e\u8005\u53ea\u5bf9\u5f53\u524d\u5ba2\u6237\u7aef\u8fde\u63a5\u751f\u6548\uff0c\u4e0d\u6307\u5b9a\u9ed8\u8ba4\u4e3a SESSION\u3002<\/p>\n<p>\u67e5\u770b\u7cfb\u7edf\u53d8\u91cf<\/p>\n<pre><code class=\"language-mysql\">SHOW [SESSION | GLOBAL] VARIABLES; # \u67e5\u770b\u5168\u90e8\n\nSHOW [SESSION | GLOBAL] VARIABLES LIKE '\u5173\u952e\u8bcd'; # \u6a21\u7cca\u5339\u914d\n\nSELECT @@[SESSION | GLOBAL] \u53d8\u91cf\u540d; # \u67e5\u770b\u6307\u5b9a\u7684<\/code><\/pre>\n<p>\u8bbe\u7f6e\u7cfb\u7edf\u53d8\u91cf<\/p>\n<pre><code class=\"language-mysql\">SET [SESSION | GLOBAL] \u53d8\u91cf\u540d = \u503c;\nSET @@[SESSION | GLOBAL] \u53d8\u91cf\u540d = \u503c;<\/code><\/pre>\n<h3><span class=\"ez-toc-section\" id=\"%E7%94%A8%E6%88%B7%E8%87%AA%E5%AE%9A%E4%B9%89%E5%8F%98%E9%87%8F\"><\/span>\u7528\u6237\u81ea\u5b9a\u4e49\u53d8\u91cf<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u7528\u6237\u81ea\u5b9a\u4e49\u53d8\u91cf\u6ca1\u6709\u5168\u5c40\u53d8\u91cf\uff0c\u53ea\u80fd\u5728\u5f53\u524d\u5ba2\u6237\u7aef\u8fde\u63a5\u751f\u6548\uff0c\u7cfb\u7edf\u53d8\u91cf\u662f\u4e24\u4e2a@\uff0c\u7528\u6237\u81ea\u5b9a\u4e49\u53d8\u91cf\u5219\u53ea\u6709\u4e00\u4e2a@\u3002<\/p>\n<p>\u8d4b\u503c<\/p>\n<pre><code class=\"language-mysql\">SET @\u53d8\u91cf\u540d = \u503c;\n\nSET @\u53d8\u91cf\u540d := \u503c;\n\nSELECT @\u53d8\u91cf\u540d := \u8868\u8fbe\u5f0f;\n\nSELECT \u5b57\u6bb5\u540d INTO @\u53d8\u91cf\u540d FROM \u8868\u540d; # \u5c06\u8868\u4e2d\u7684\u5b57\u6bb5\u503c\u8d4b\u503c\u7ed9\u53d8\u91cf<\/code><\/pre>\n<p>\u67e5\u770b\u503c<\/p>\n<pre><code class=\"language-mysql\">SELECT @\u53d8\u91cf\u540d;<\/code><\/pre>\n<h3><span class=\"ez-toc-section\" id=\"%E5%B1%80%E9%83%A8%E5%8F%98%E9%87%8F\"><\/span>\u5c40\u90e8\u53d8\u91cf<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u53ef\u4ee5\u5728\u50a8\u5b58\u8fc7\u7a0b\u4e2d\u4f7f\u7528\uff0c\u4f5c\u7528\u8303\u56f4\u4ecb\u4e8e BEGIN \u548c END \u4e4b\u95f4\u3002<\/p>\n<p>\u5b9a\u4e49\u5c40\u90e8\u53d8\u91cf\uff0c\u8d4b\u503c\u64cd\u4f5c\u540c\u4e0a<\/p>\n<pre><code class=\"language-mysql\">DECLARE \u53d8\u91cf\u540d \u53d8\u91cf\u7c7b\u578b [DEFAULT ...];<\/code><\/pre>\n<p>\u6f14\u793a<\/p>\n<pre><code class=\"language-mysql\">DELIMITER $$\nCREATE PROCEDURE p1()\nBEGIN\n    DECLARE info_count int DEFAULT 0; # \u5b9a\u4e49\u5c40\u90e8\u53d8\u91cf info_count\uff0c\u9ed8\u8ba4\u503c\u4e3a 0\n    SELECT count(*) INTO info_count FROM info;\n    SELECT info_count;\nEND $$\nDELIMITER ;\n\nCALL p1();<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708782165157.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 766px; --smush-placeholder-aspect-ratio: 766\/354;\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"%E5%AD%98%E5%82%A8%E8%BF%87%E7%A8%8B%E7%9A%84%E5%8F%82%E6%95%B0%E4%BC%A0%E9%80%92\"><\/span>\u5b58\u50a8\u8fc7\u7a0b\u7684\u53c2\u6570\u4f20\u9012<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u7c7b\u4f3c\u4e8e\u4e00\u822c\u53d8\u6210\u8bed\u8a00\u4e2d\u51fd\u6570\u4f20\u5165\u53c2\u6570\u548c\u8fd4\u56de\u503c\u3002<\/p>\n<p>\u8fd9\u91cc\u7ed9\u51fa\u4e00\u4e2a\u4f8b\u5b50\uff0c\u521b\u5efa\u4e00\u4e2a\u5b58\u50a8\u8fc7\u7a0b p2\uff0c\u6709\u4e09\u4e2a\u53c2\u6570\uff0c\u5206\u522b\u662f\u4f20\u5165\u53c2\u6570 in_arg\uff0c\u4f20\u51fa\u53c2\u6570 out_arg\uff0c\u4f20\u5165\u4f20\u51fa\u53c2\u6570 inout_arg<\/p>\n<pre><code class=\"language-mysql\">DELIMITER $$\nCREATE PROCEDURE p2(IN in_arg int,\n                    OUT out_arg int,\n                    INOUT inout_arg int)\nBEGIN\n    SET out_arg := in_arg + inout_arg;\n    SET inout_arg := 2 * out_arg;\nEND $$\nDELIMITER ;<\/code><\/pre>\n<p>\u8c03\u7528\u5b58\u50a8\u8fc7\u7a0b<\/p>\n<pre><code class=\"language-mysql\">SET @inout = 3;\nCALL p2(7, @out, @inout);\nSELECT @out, @inout;<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708829564187.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 259px; --smush-placeholder-aspect-ratio: 259\/112;\" \/><\/p>\n<h2><span class=\"ez-toc-section\" id=\"%E6%9D%A1%E4%BB%B6%E5%88%A4%E6%96%AD\"><\/span>\u6761\u4ef6\u5224\u65ad<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3><span class=\"ez-toc-section\" id=\"IF\"><\/span>IF<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<pre><code class=\"language-mysql\">IF \u6761\u4ef61 THEN\n...\nELSEIF \u6761\u4ef62 THEN\n...\nELSE\n...\nEND IF;<\/code><\/pre>\n<p>\u793a\u4f8b<\/p>\n<pre><code class=\"language-mysql\">DELIMITER $$\nCREATE PROCEDURE p3(score float)\nBEGIN\n    IF score > 90 THEN\n        SELECT '\u4f18\u79c0';\n    ELSEIF score > 75 THEN\n        SELECT '\u826f\u597d';\n    ELSEIF score > 60 THEN\n        SELECT '\u53ca\u683c';\n    ELSE\n        SELECT '\u4e0d\u53ca\u683c';\n    END IF;\nEND $$\nDELIMITER ;\n\nCALL p3(85);<\/code><\/pre>\n<p><img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708832027328.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 138px; --smush-placeholder-aspect-ratio: 138\/80;\" \/><\/p>\n<h3><span class=\"ez-toc-section\" id=\"CASE\"><\/span>CASE<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u4e24\u79cd\u8bed\u6cd5\u53c2\u8003\u6d41\u7a0b\u51fd\u6570\u90e8\u5206\uff1a<a href=\"https:\/\/blog.iyatt.com\/?p=12631#_%E6%B5%81%E7%A8%8B%E5%87%BD%E6%95%B0\">https:\/\/blog.iyatt.com\/?p=12631#_%E6%B5%81%E7%A8%8B%E5%87%BD%E6%95%B0<\/a><\/p>\n<p>\u4f8b\u4e00<\/p>\n<pre><code class=\"language-mysql\">DELIMITER $$\nCREATE PROCEDURE p4(score float)\nBEGIN\n    CASE\n        WHEN score > 90 THEN\n            SELECT '\u4f18\u79c0';\n        WHEN score > 75 THEN\n            SELECT '\u826f\u597d';\n        WHEN score > 60 THEN\n            SELECT '\u53ca\u683c';\n        ELSE\n            SELECT '\u4e0d\u53ca\u683c';\n    END CASE;\nEND $$\nDELIMITER ;\n\nCALL p4(59);<\/code><\/pre>\n<p>\u4f8b\u4e8c<\/p>\n<pre><code class=\"language-mysql\">DELIMITER $$\nCREATE PROCEDURE p5(grades char(1))\nBEGIN\n    CASE grades\n        WHEN 'A' THEN\n            SELECT '\u4f18\u79c0';\n        WHEN 'B' THEN\n            SELECT '\u826f\u597d';\n        WHEN 'C' THEN\n            SELECT '\u4e00\u822c';\n        ELSE\n            SELECT '\u672a\u77e5';\n    END CASE;\nEND $$\nDELIMITER ;\n\nCALL p5('C');<\/code><\/pre>\n<h2><span class=\"ez-toc-section\" id=\"%E5%BE%AA%E7%8E%AF\"><\/span>\u5faa\u73af<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3><span class=\"ez-toc-section\" id=\"WHILE\"><\/span>WHILE<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<pre><code class=\"language-mysql\">WHILE \u6761\u4ef6 DO\n    ...\nEND WHILE<\/code><\/pre>\n<p>\u793a\u4f8b<br \/>\n\u7d2f\u52a0 1-100<\/p>\n<pre><code class=\"language-mysql\">DELIMITER $$\nCREATE PROCEDURE p6(n int)\nBEGIN\n    DECLARE sum int DEFAULT 0;\n    DECLARE counter int DEFAULT 0;\n    WHILE counter < n DO\n        SET counter := counter + 1;\n        SET sum := sum + counter;\n    END WHILE;\n    SELECT sum;\nEND $$\nDELIMITER ;\n\nCALL p6(100);<\/code><\/pre>\n<h3><span class=\"ez-toc-section\" id=\"REPEAT\"><\/span>REPEAT<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>WHILE \u662f\u6ee1\u8db3\u6761\u4ef6\u6267\u884c\u5faa\u73af\uff0cREPEAT \u662f\u6ee1\u8db3\u6761\u4ef6\u9000\u51fa\u5faa\u73af<\/p>\n<pre><code class=\"language-mysql\">REPEAT\n    ...\n    UNTIL \u6761\u4ef6\nEND REPEAT;<\/code><\/pre>\n<p>\u793a\u4f8b<\/p>\n<pre><code class=\"language-mysql\">DELIMITER $$\nCREATE PROCEDURE p7(n int)\nBEGIN\n    DECLARE sum int DEFAULT 0;\n    REPEAT\n        SET sum := sum + n;\n        SET n := n - 1;\n    UNTIL n = 0\n    END REPEAT;\n    SELECT sum;\nEND $$\nDELIMITER ;\n\nCALL p7(100);<\/code><\/pre>\n<h3><span class=\"ez-toc-section\" id=\"LOOP\"><\/span>LOOP<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>LOOP \u5faa\u73af\u672c\u8eab\u4e0d\u5e26\u9000\u51fa\u6761\u4ef6\u5224\u65ad\uff0c\u662f\u53ef\u4ee5\u5b9e\u73b0\u65e0\u9650\u5faa\u73af\u7684\uff0c\u901a\u8fc7\u81ea\u884c\u8c03\u7528 LEAVE \u9000\u51fa\u5faa\u73af\uff0c\u6216\u8005\u8c03\u7528 ITERATE \u8df3\u8fc7\u672c\u8f6e\u5faa\u73af\uff0c\u50cf\u4e00\u822c\u7f16\u7a0b\u8bed\u8a00\u91cc\u7684 break \u548c continue\u3002<\/p>\n<pre><code class=\"language-mysql\">\u81ea\u5b9a\u4e49\u5faa\u73af\u6807\u7b7e\u540d: LOOP\n\nEND LOPP \u6807\u7b7e\u540d;<\/code><\/pre>\n<p>\u793a\u4f8b<br \/>\n\u7d2f\u52a0 1-100 \u7684\u5076\u6570<\/p>\n<pre><code class=\"language-mysql\">DELIMITER $$\nCREATE PROCEDURE p8(n int)\nBEGIN\n    DECLARE sum int DEFAULT 0;\n    my_sum: LOOP\n        IF n <= 0 THEN\n            LEAVE my_sum; # \u9000\u51fa\u5faa\u73af\n        END IF ;\n\n        IF n % 2 = 1 THEN\n            SET n := n -1;\n            ITERATE my_sum; # \u8df3\u8fc7\u672c\u8f6e\u5faa\u73af\n        END IF ;\n\n        SET sum := sum + n;\n        SET n := n - 1;\n    END LOOP my_sum;\n    SELECT sum;\nEND $$\nDELIMITER ;\n\nCALL p8(100);<\/code><\/pre>\n<h2><span class=\"ez-toc-section\" id=\"%E6%B8%B8%E6%A0%87%E5%92%8C%E6%9D%A1%E4%BB%B6%E5%A4%84%E7%90%86%E7%A8%8B%E5%BA%8F\"><\/span>\u6e38\u6807\u548c\u6761\u4ef6\u5904\u7406\u7a0b\u5e8f<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u6e38\u6807\u7684\u4f5c\u7528\u548c\u4e00\u822c\u7f16\u7a0b\u8bed\u8a00\u91cc\u9762\u7684\u8fed\u4ee3\u5668\u7c7b\u4f3c\u3002<\/p>\n<p>\u58f0\u660e<\/p>\n<pre><code class=\"language-mysql\">DECLARE \u6e38\u6807\u540d\u79f0 CURSOR FOR \u67e5\u8be2\u8bed\u53e5;<\/code><\/pre>\n<p>\u6253\u5f00<\/p>\n<pre><code class=\"language-mysql\">OPEN \u6e38\u6807\u540d\u79f0;<\/code><\/pre>\n<p>\u83b7\u53d6\u6e38\u6807\u8bb0\u5f55<\/p>\n<pre><code class=\"language-mysql\">FETCH \u6e38\u6807\u540d\u79f0 INTO \u53d8\u91cf;<\/code><\/pre>\n<p>\u5173\u95ed\u6e38\u6807<\/p>\n<pre><code class=\"language-mysql\">CLOSE \u6e38\u6807\u540d\u79f0;<\/code><\/pre>\n<p>\u6761\u4ef6\u5904\u7406\u7a0b\u5e8f<br \/>\n\u8fd9\u4e2a\u6709\u70b9\u50cf Linux \u6355\u83b7\u4fe1\u53f7<\/p>\n<pre><code class=\"language-mysql\">DECLARE hander_action HANDLER FOR condition_value statement;<\/code><\/pre>\n<p>hander_action\uff1a<\/p>\n<ul>\n<li>CONTINUE \u7ee7\u7eed\u6267\u884c\u5f53\u524d\u7a0b\u5e8f<\/li>\n<li>EXIT \u7ec8\u6b62\u6267\u884c\u5f53\u524d\u7a0b\u5e8f<\/li>\n<\/ul>\n<p>condition_value\uff1a<\/p>\n<ul>\n<li>SQLSTATE sqlstate_value \u72b6\u6001\u7801\uff0c\u5982 02000<\/li>\n<li>SQLWARNING \u6240\u6709\u4ee5 01 \u5f00\u5934\u7684 SQLSTATE \u7684\u7b80\u5199<\/li>\n<li>NOT FOUND \u6240\u6709\u4ee5 02 \u5f00\u5934\u7684 SQLSTATE \u7684\u7b80\u5199<\/li>\n<li>SQLEXCEPTIO \u6240\u6709\u6ca1\u6709\u88ab SQLWARNING \u6216 NOT FOUND \u6355\u83b7\u7684 SQLSTATE \u7684\u7b80\u5199<\/li>\n<\/ul>\n<p>\u793a\u4f8b<br \/>\n\u67e5\u8be2 info \u8868\u7684 name \u5217\u548c age \u5217\uff0c\u5e76\u5c06\u5b83\u4eec\u5b58\u5230\u53e6\u5916\u4e00\u5f20\u8868 temp_table \u4e2d<\/p>\n<pre><code class=\"language-mysql\">DELIMITER $$\nCREATE PROCEDURE p9()\nBEGIN\n    DECLARE name1 char(2);\n    DECLARE age1 tinyint;\n    DECLARE my_cursor CURSOR FOR SELECT name, age FROM info; # \u58f0\u660e\u4e00\u4e2a\u904d\u5386 info \u8868 name\u3001age \u5217\u7684\u6e38\u6807\n    DECLARE EXIT HANDLER FOR SQLSTATE '02000' CLOSE my_cursor; # \u6ca1\u6709\u8fd9\u4e2a\u6761\u4ef6\u5904\u7406\u7a0b\u5e8f\uff0c\u5f53 FETCH \u904d\u5386\u5230\u6ca1\u6709\u6570\u636e\u7684\u4f4d\u7f6e\u4f1a\u62a5\u9519 02000\uff0c\u6240\u4ee5\u8fd9\u91cc\u6355\u83b7\u8fd9\u4e2a\u72b6\u6001\u7801\uff0c\u6765\u4e3b\u52a8\u6267\u884c\u9000\u51fa\n\n    OPEN my_cursor; # \u6253\u5f00\u6e38\u6807\n\n    # \u4e34\u65f6\u8868\n    DROP TABLE IF EXISTS temp_table;\n\n    CREATE TABLE temp_table (\n        id tinyint PRIMARY KEY AUTO_INCREMENT,\n        name char(2),\n        age tinyint\n    );\n\n    WHILE TRUE DO\n        FETCH my_cursor INTO name1, age1; # \u4ece\u6e38\u6807\u4e2d\u53d6\u503c\n        INSERT INTO temp_table (name, age) VALUES (name1, age1); # \u5c06\u53d6\u503c\u63d2\u5165\u65b0\u8868\u4e2d\n    END WHILE ;\n\n    CLOSE my_cursor; # \u5173\u95ed\u6e38\u6807\n\nEND $$\nDELIMITER ;\n\nCALL p9();<\/code><\/pre>\n<p>info \u8868<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708858167062.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 440px; --smush-placeholder-aspect-ratio: 440\/124;\" \/><\/p>\n<p>\u65b0\u5efa\u7684\u8868<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708858190271.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 338px; --smush-placeholder-aspect-ratio: 338\/140;\" \/><\/p>\n<h1><span class=\"ez-toc-section\" id=\"%E5%AD%98%E5%82%A8%E5%87%BD%E6%95%B0\"><\/span>\u5b58\u50a8\u51fd\u6570<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>\u5b58\u50a8\u51fd\u6570\u7b49\u540c\u4e8e\u6709\u4e13\u7528\u8fd4\u56de\u503c\u7684\u5b58\u50a8\u8fc7\u7a0b\uff0c\u5b58\u50a8\u51fd\u6570\u80fd\u505a\u7684\uff0c\u50a8\u5b58\u8fc7\u7a0b\u4e5f\u80fd\u5b9e\u73b0\u3002\u5b58\u50a8\u51fd\u6570\u8981\u6c42\u5fc5\u987b\u6709\u8fd4\u56de\u503c\uff0c\u800c\u5b58\u50a8\u8fc7\u7a0b\u53ef\u4ee5\u901a\u8fc7\u53c2\u6570\u8fdb\u884c\u8fd4\u56de\uff0c\u4e5f\u53ef\u4ee5\u4e0d\u7528\u3002<\/p>\n<pre><code class=\"language-mysql\">CREATE FUNCTION \u5b58\u50a8\u51fd\u6570\u540d\u79f0([\u53c2\u6570\u5217\u8868])\nRETURNS type [characteristic]\nBEGIN\n    ...\n    RETURN ...;\nEND<\/code><\/pre>\n<p>characteristic\uff1a<\/p>\n<ul>\n<li>DETERMINSTIC \u76f8\u540c\u7684\u8f93\u5165\u53c2\u6570\u603b\u662f\u4ea7\u751f\u76f8\u540c\u7684\u7ed3\u679c<\/li>\n<li>NO SQL \u4e0d\u5305\u542b SQL \u8bed\u53e5<\/li>\n<li>READS SQL DATA \u5305\u542b\u8bfb\u53d6\u6570\u636e\u7684\u8bed\u53e5\uff0c\u4f46\u4e0d\u5305\u542b\u5199\u5165\u6570\u636e\u7684\u8bed\u53e5<\/li>\n<\/ul>\n<p>\u793a\u4f8b<br \/>\n\u4ece1\u7d2f\u52a0\u5230100<\/p>\n<pre><code class=\"language-mysql\">DELIMITER $$\nCREATE FUNCTION f(n int)\nRETURNS int DETERMINISTIC\nBEGIN\n    DECLARE sum int DEFAULT 0;\n    WHILE n > 0 DO\n        SET sum := sum + n;\n        SET n := n - 1;\n    END WHILE ;\n    RETURN sum;\nEND $$\nDELIMITER ;\n\nSET @sum = f(100);\nSELECT @sum;<\/code><\/pre>\n<h1><span class=\"ez-toc-section\" id=\"%E8%A7%A6%E5%8F%91%E5%99%A8\"><\/span>\u89e6\u53d1\u5668<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<p>\u7c7b\u4f3c\u4e8e\u4e8b\u4ef6\u76d1\u542c\uff0c\u51fa\u73b0\u63d2\u5165\u3001\u4fee\u6539\u3001\u5220\u9664\u64cd\u4f5c\u7684\u65f6\u5019\u53ef\u4ee5\u5b8c\u6210\u6307\u5b9a\u64cd\u4f5c\uff0c\u4f7f\u7528\u522b\u540d OLD \u548c NEW \u5f15\u7528\u53d1\u751f\u53d8\u5316\u7684\u5185\u5bb9\u3002<br \/>\n\u76ee\u524d\u53ea\u652f\u6301\u884c\u7ea7\u89e6\u53d1\u5668\uff0c\u4e0d\u652f\u6301\u8bed\u53e5\u7ea7\u89e6\u53d1\u5668\u3002\u6bd4\u5982\u4e00\u4e2a\u63d2\u5165\u8bed\u53e5\u63d2\u5165\u591a\u884c\u6570\u636e\uff0c\u6bcf\u63d2\u5165\u4e00\u884c\u5c31\u4f1a\u89e6\u53d1\u4e00\u6b21\uff0c\u800c\u4e0d\u662f\u6574\u4e2a\u8bed\u53e5\u53ea\u89e6\u53d1\u4e00\u6b21\u3002<\/p>\n<ul>\n<li>INSERT \u89e6\u53d1\u5668\uff1aNEW \u8868\u793a\u5c06\u8981\u6216\u8005\u5df2\u7ecf\u65b0\u589e\u7684\u6570\u636e<\/li>\n<li>UPDATE \u89e6\u53d1\u5668\uff1aOLD \u8868\u793a\u4fee\u6539\u524d\u7684\u6570\u636e\uff0cNEW \u8868\u793a\u5c06\u8981\u6216\u8005\u5df2\u7ecf\u4fee\u6539\u540e\u7684\u6570\u636e<\/li>\n<li>DELETE \u89e6\u53d1\u5668\uff1aOLD \u8868\u793a\u5c06\u8981\u6216\u8005\u5df2\u7ecf\u5220\u9664\u7684\u6570\u636e<\/li>\n<\/ul>\n<p>\u521b\u5efa<\/p>\n<pre><code class=\"language-mysql\">CREATE TRIGGER \u89e6\u53d1\u5668\u540d\u5b57\nBEFORE \/ AFTER INSERT \/ UPDATE \/ DELETE\nON \u8868\u540d FOR EACH ROW\nBEGIN\n    ...\nEND;<\/code><\/pre>\n<p>\u67e5\u770b<\/p>\n<pre><code class=\"language-mysql\">SHOW TRIGGERS;<\/code><\/pre>\n<p>\u5220\u9664<\/p>\n<pre><code class=\"language-mysql\">DROP TRIGGER \u89e6\u53d1\u5668\u540d\u5b57;<\/code><\/pre>\n<p>\u793a\u4f8b<br \/>\n\u521b\u5efa\u4e00\u5f20\u8868 new_table\uff0c\u7136\u540e\u521b\u5efa\u4e00\u5f20\u65e5\u5fd7\u8868 user_logs\u3002\u521b\u5efa\u4e00\u4e2a\u89e6\u53d1\u5668\uff0c\u5728\u5bf9 new_table \u6267\u884c\u63d2\u5165\u64cd\u4f5c\u540e\u5411 user_logs \u65e5\u5fd7\u8868\u5199\u5165\u64cd\u4f5c\u7c7b\u578b\uff0c\u64cd\u4f5c\u65f6\u95f4\uff0c\u64cd\u4f5c\u7684 ID\uff0c\u64cd\u4f5c\u5199\u5165\u4e86\u4ec0\u4e48\u5185\u5bb9\u3002<\/p>\n<pre><code class=\"language-mysql\">CREATE TABLE new_table (\n    id tinyint PRIMARY KEY AUTO_INCREMENT,\n    name char(2),\n    age tinyint\n);\n\nCREATE TABLE user_logs (\n    id tinyint NOT NULL PRIMARY KEY AUTO_INCREMENT,\n    operation varchar(20) NOT NULL COMMENT '\u64cd\u4f5c\u7c7b\u578b',\n    operate_time datetime NOT NULL COMMENT '\u64cd\u4f5c\u65f6\u95f4',\n    operate_id tinyint NOT NULL COMMENT '\u64cd\u4f5c\u7684 ID',\n    operate_params varchar(500) COMMENT '\u64cd\u4f5c\u53c2\u6570'\n);\n\nDELIMITER $$\nCREATE TRIGGER new_table_trigger\n    AFTER INSERT ON new_table FOR EACH ROW\nBEGIN\n    INSERT INTO user_logs VALUES\n                              (NULL, 'insert', now(), NEW.id, concat('\u63d2\u5165\u7684\u6570\u636e\u5185\u5bb9\u4e3a\uff1aid=', NEW.id, 'name=', NEW.name, 'age=', NEW.age));\nEND $$\nDELIMITER ;\n\nINSERT INTO new_table (name, age) VALUES\n                          ('\u5c0f\u5f3a', 10),\n                          ('\u5c0f\u7ea2', 20);<\/code><\/pre>\n<p>\u5728\u8fdb\u884c\u63d2\u5165\u64cd\u4f5c\u540e\uff0c\u65e5\u5fd7\u8868\u4e2d\u901a\u8fc7\u89e6\u53d1\u5668\u81ea\u52a8\u8bb0\u5f55\u4e86\u64cd\u4f5c\u5185\u5bb9<br \/>\n<img decoding=\"async\" data-src=\"https:\/\/blog.iyatt.com\/wp-content\/uploads\/2024\/02\/image-1708871059214.png\" alt=\"file\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" style=\"--smush-placeholder-width: 950px; --smush-placeholder-aspect-ratio: 950\/175;\" \/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u73af\u5883 MySQL \u793e\u533a\u7248 8.0.35 IDEA 2023\uff1a\u4e4b\u524d\u5b66 Kotlin \u548c Android \u5f00\u53d1\u7684\u65f6 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"zakra_page_container_layout":"customizer","zakra_page_sidebar_layout":"customizer","zakra_remove_content_margin":false,"zakra_sidebar":"customizer","zakra_transparent_header":"customizer","zakra_logo":0,"zakra_main_header_style":"default","zakra_menu_item_color":"","zakra_menu_item_hover_color":"","zakra_menu_item_active_color":"","zakra_menu_active_style":"","zakra_page_header":true,"_lmt_disableupdate":"no","_lmt_disable":"no","footnotes":""},"categories":[1],"tags":[],"class_list":["post-12631","post","type-post","status-publish","format-standard","hentry","category-all"],"modified_by":"IYATT-yx","_links":{"self":[{"href":"https:\/\/blog.iyatt.com\/index.php?rest_route=\/wp\/v2\/posts\/12631","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.iyatt.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.iyatt.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.iyatt.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.iyatt.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=12631"}],"version-history":[{"count":0,"href":"https:\/\/blog.iyatt.com\/index.php?rest_route=\/wp\/v2\/posts\/12631\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.iyatt.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=12631"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.iyatt.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=12631"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.iyatt.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=12631"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}