{"id":6269,"date":"2024-11-14T13:58:54","date_gmt":"2024-11-14T05:58:54","guid":{"rendered":"https:\/\/fwq.ai\/blog\/6269\/"},"modified":"2024-11-14T13:58:54","modified_gmt":"2024-11-14T05:58:54","slug":"sql%e5%a6%82%e4%bd%95%e8%bf%9b%e8%a1%8c%e4%bc%98%e5%8c%96","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/6269\/","title":{"rendered":"sql\u5982\u4f55\u8fdb\u884c\u4f18\u5316"},"content":{"rendered":"<p><strong>\u5982\u4f55\u4f18\u5316 sql \u67e5\u8be2<\/strong><\/p>\n<p><strong>\u4f18\u5316 SQL \u67e5\u8be2\u7684\u6b65\u9aa4\uff1a<\/strong><\/p>\n<p><strong>1. \u5206\u6790\u67e5\u8be2<\/strong><\/p>\n<ul>\n<li>\u627e\u51fa\u9700\u8981\u4f18\u5316\u7684\u9ad8\u8017\u65f6\u67e5\u8be2\u3002<\/li>\n<li>\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u6765\u67e5\u770b\u67e5\u8be2\u6267\u884c\u8ba1\u5212\u3002<\/li>\n<li>\u8bc6\u522b\u67e5\u8be2\u4e2d\u7684\u74f6\u9888\uff0c\u4f8b\u5982\u8868\u626b\u63cf\u3001\u7d22\u5f15\u626b\u63cf\u6216\u5b50\u67e5\u8be2\u3002<\/li>\n<\/ul>\n<p><strong>2. \u4f18\u5316\u8868\u7ed3\u6784<\/strong><\/p>\n<ul>\n<li>\u786e\u4fdd\u8868\u7684\u5217\u6570\u636e\u7c7b\u578b\u4e0e\u5b9e\u9645\u6570\u636e\u5339\u914d\u3002<\/li>\n<li>\u6dfb\u52a0\u76f8\u5173\u7d22\u5f15\u4ee5\u52a0\u901f\u6570\u636e\u68c0\u7d22\u3002<\/li>\n<li>\u907f\u514d\u4e0d\u5fc5\u8981\u7684\u5217\uff0c\u56e0\u4e3a\u5b83\u4f1a\u51cf\u6162\u67e5\u8be2\u901f\u5ea6\u3002<\/li>\n<\/ul>\n<p><strong>3. \u4f18\u5316\u67e5\u8be2\u8bed\u53e5<\/strong><\/p>\n<ul>\n<li>\u4f7f\u7528 SELECT * \u65f6\u5e94\u660e\u786e\u6307\u5b9a\u9700\u8981\u7684\u5217\u3002<\/li>\n<li>\u5728 WHERE \u5b50\u53e5\u4e2d\u4f7f\u7528\u7d22\u5f15\u5217\u8fdb\u884c\u8fc7\u6ee4\u3002<\/li>\n<li>\u4f7f\u7528 UNION ALL \u4ee3\u66ff UNION \u4ee5\u63d0\u9ad8\u6027\u80fd\u3002<\/li>\n<\/ul>\n<p><strong>4. \u4f7f\u7528\u9002\u5f53\u7684\u8fde\u63a5\u7c7b\u578b<\/strong><\/p>\n<ul>\n<li>\u9009\u62e9\u5408\u9002\u7684\u8fde\u63a5\u7c7b\u578b\uff08INNER JOIN\u3001LEFT JOIN\u3001RIGHT JOIN\uff09\u3002<\/li>\n<li>\u4f7f\u7528 EXISTS \u6216 IN \u4ee3\u66ff\u5d4c\u5957\u5b50\u67e5\u8be2\u3002<\/li>\n<\/ul>\n<p><strong>5. \u51cf\u5c11\u5b50\u67e5\u8be2<\/strong><\/p>\n<ul>\n<li>\u5c3d\u53ef\u80fd\u4f7f\u7528 JOIN \u4ee3\u66ff\u5b50\u67e5\u8be2\u3002<\/li>\n<li>\u5c06\u590d\u6742\u5b50\u67e5\u8be2\u5206\u89e3\u6210\u66f4\u5c0f\u7684\u67e5\u8be2\u3002<\/li>\n<\/ul>\n<p><strong>6. \u4f7f\u7528\u4e34\u65f6\u8868<\/strong><\/p>\n<ul>\n<li>\u5bf9\u4e8e\u9700\u8981\u5927\u91cf\u91cd\u590d\u8ba1\u7b97\u7684\u7ed3\u679c\uff0c\u8003\u8651\u4f7f\u7528\u4e34\u65f6\u8868\u3002<\/li>\n<li>\u53ef\u4ee5\u5728\u4e34\u65f6\u8868\u4e0a\u521b\u5efa\u7d22\u5f15\u4ee5\u52a0\u5feb\u67e5\u8be2\u901f\u5ea6\u3002<\/li>\n<\/ul>\n<p><strong>7. \u7f13\u5b58\u7ed3\u679c<\/strong><\/p>\n<ul>\n<li>\u5bf9\u4e8e\u7ecf\u5e38\u8bbf\u95ee\u7684\u6570\u636e\uff0c\u53ef\u4ee5\u5c06\u67e5\u8be2\u7ed3\u679c\u7f13\u5b58\u8d77\u6765\u3002<\/li>\n<li>\u7f13\u5b58\u673a\u5236\u53ef\u4ee5\u51cf\u5c11\u6570\u636e\u5e93\u8d1f\u8f7d\uff0c\u63d0\u9ad8\u67e5\u8be2\u901f\u5ea6\u3002<\/li>\n<\/ul>\n<p><strong>8. \u5e76\u884c\u5904\u7406<\/strong><\/p>\n<ul>\n<li>\u5982\u679c\u53ef\u80fd\uff0c\u5c06\u67e5\u8be2\u62c6\u5206\u6210\u591a\u4e2a\u5e76\u884c\u6267\u884c\u7684\u5b50\u67e5\u8be2\u3002<\/li>\n<li>\u8fd9\u53ef\u4ee5\u63d0\u9ad8\u591a\u6838\u5904\u7406\u5668\u7684\u5229\u7528\u7387\uff0c\u7f29\u77ed\u67e5\u8be2\u65f6\u95f4\u3002<\/li>\n<\/ul>\n<p><strong>9. \u4f7f\u7528\u6570\u636e\u5e93\u4f18\u5316\u5de5\u5177<\/strong><\/p>\n<ul>\n<li>\u8003\u8651\u4f7f\u7528\u6570\u636e\u5e93\u4f18\u5316\u5de5\u5177\uff08\u4f8b\u5982 pgbadger\uff09\u6765\u8bc6\u522b\u548c\u89e3\u51b3\u67e5\u8be2\u6027\u80fd\u95ee\u9898\u3002<\/li>\n<li>\u8fd9\u4e9b\u5de5\u5177\u53ef\u4ee5\u63d0\u4f9b\u8be6\u7ec6\u7684\u62a5\u544a\uff0c\u5e2e\u52a9\u5feb\u901f\u627e\u51fa\u9700\u8981\u4f18\u5316\u7684\u67e5\u8be2\u3002<\/li>\n<\/ul>\n<p>\u4ee5\u4e0a\u5c31\u662fsql\u5982\u4f55\u8fdb\u884c\u4f18\u5316\u7684\u8be6\u7ec6\u5185\u5bb9\uff0c\u66f4\u591a\u8bf7\u5173\u6ce8\u7c73\u4e91\u7f51\u5176\u5b83\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5982\u4f55\u4f18\u5316 sql \u67e5\u8be2 \u4f18\u5316 SQL \u67e5\u8be2\u7684\u6b65\u9aa4\uff1a 1. \u5206\u6790\u67e5\u8be2 \u627e\u51fa\u9700\u8981\u4f18\u5316\u7684\u9ad8\u8017\u65f6\u67e5\u8be2\u3002 \u4f7f\u7528 EXPLAIN \u547d\u4ee4\u6765\u67e5\u770b\u67e5\u8be2\u6267\u884c\u8ba1\u5212\u3002 \u8bc6\u522b\u67e5\u8be2\u4e2d\u7684\u74f6\u9888\uff0c\u4f8b\u5982\u8868\u626b\u63cf\u3001\u7d22\u5f15\u626b\u63cf\u6216\u5b50\u67e5\u8be2\u3002 2. \u4f18\u5316\u8868\u7ed3\u6784 \u786e\u4fdd\u8868\u7684\u5217\u6570\u636e\u7c7b\u578b\u4e0e\u5b9e\u9645\u6570\u636e\u5339\u914d\u3002 \u6dfb\u52a0\u76f8\u5173\u7d22\u5f15\u4ee5\u52a0\u901f\u6570\u636e\u68c0\u7d22\u3002 \u907f\u514d\u4e0d\u5fc5\u8981\u7684\u5217\uff0c\u56e0\u4e3a\u5b83\u4f1a\u51cf\u6162\u67e5\u8be2\u901f\u5ea6\u3002 3. \u4f18\u5316\u67e5\u8be2\u8bed\u53e5 \u4f7f\u7528 SELECT * \u65f6\u5e94\u660e\u786e\u6307\u5b9a\u9700\u8981\u7684\u5217\u3002 \u5728 WHERE \u5b50\u53e5\u4e2d\u4f7f\u7528\u7d22\u5f15\u5217\u8fdb\u884c\u8fc7\u6ee4\u3002 \u4f7f\u7528 UNION ALL \u4ee3\u66ff UNION \u4ee5\u63d0\u9ad8\u6027\u80fd\u3002 4. \u4f7f\u7528\u9002\u5f53\u7684\u8fde\u63a5\u7c7b\u578b \u9009\u62e9\u5408\u9002\u7684\u8fde\u63a5\u7c7b\u578b\uff08INNER JOIN\u3001LEFT JOIN\u3001RIGHT JOIN\uff09\u3002 \u4f7f\u7528 EXISTS \u6216 IN \u4ee3\u66ff\u5d4c\u5957\u5b50\u67e5\u8be2\u3002 5. \u51cf\u5c11\u5b50\u67e5\u8be2 \u5c3d\u53ef\u80fd\u4f7f\u7528 JOIN \u4ee3\u66ff\u5b50\u67e5\u8be2\u3002 \u5c06\u590d\u6742\u5b50\u67e5\u8be2\u5206\u89e3\u6210\u66f4\u5c0f\u7684\u67e5\u8be2\u3002 6. \u4f7f\u7528\u4e34\u65f6\u8868 \u5bf9\u4e8e\u9700\u8981\u5927\u91cf\u91cd\u590d\u8ba1\u7b97\u7684\u7ed3\u679c\uff0c\u8003\u8651\u4f7f\u7528\u4e34\u65f6\u8868\u3002 \u53ef\u4ee5\u5728\u4e34\u65f6\u8868\u4e0a\u521b\u5efa\u7d22\u5f15\u4ee5\u52a0\u5feb\u67e5\u8be2\u901f\u5ea6\u3002 7. [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[],"class_list":["post-6269","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/6269","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/comments?post=6269"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/6269\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=6269"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=6269"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=6269"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}