{"id":187478,"date":"2024-11-11T14:36:24","date_gmt":"2024-11-11T06:36:24","guid":{"rendered":"https:\/\/server.hk\/cnblog\/187478\/"},"modified":"2024-11-11T14:36:25","modified_gmt":"2024-11-11T06:36:25","slug":"%e6%95%b8%e6%93%9a%e5%ba%ab%e6%80%a7%e8%83%bd%e5%84%aa%e5%8c%96%e4%b9%8bsql%e8%aa%9e%e5%8f%a5%e5%84%aa%e5%8c%96%ef%bc%88%e4%b8%8b%ef%bc%89","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/187478\/","title":{"rendered":"\u6578\u64da\u5eab\u6027\u80fd\u512a\u5316\u4e4bSQL\u8a9e\u53e5\u512a\u5316\uff08\u4e0b\uff09"},"content":{"rendered":"<h1 id=\"%e6%95%b8%e6%93%9a%e5%ba%ab%e6%80%a7%e8%83%bd%e5%84%aa%e5%8c%96%e4%b9%8bsql%e8%aa%9e%e5%8f%a5%e5%84%aa%e5%8c%96%ef%bc%88%e4%b8%8b%ef%bc%89-cVCuwLmuCz\">\u6578\u64da\u5eab\u6027\u80fd\u512a\u5316\u4e4bSQL\u8a9e\u53e5\u512a\u5316\uff08\u4e0b\uff09<\/h1>\n<p>\u5728\u524d\u4e00\u7bc7\u6587\u7ae0\u4e2d\uff0c\u6211\u5011\u63a2\u8a0e\u4e86\u6578\u64da\u5eab\u6027\u80fd\u512a\u5316\u7684\u57fa\u672c\u6982\u5ff5\uff0c\u4e26\u4ecb\u7d39\u4e86\u4e00\u4e9b\u5e38\u898b\u7684SQL\u8a9e\u53e5\u512a\u5316\u6280\u5de7\u3002\u5728\u9019\u7bc7\u6587\u7ae0\u4e2d\uff0c\u6211\u5011\u5c07\u6df1\u5165\u63a2\u8a0e\u66f4\u591a\u7684SQL\u8a9e\u53e5\u512a\u5316\u7b56\u7565\uff0c\u5e6b\u52a9\u958b\u767c\u8005\u548c\u6578\u64da\u5eab\u7ba1\u7406\u54e1\u63d0\u5347\u6578\u64da\u5eab\u7684\u6027\u80fd\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8%e7%b4%a2%e5%bc%95%e4%be%86%e5%8a%a0%e9%80%9f%e6%9f%a5%e8%a9%a2-cVCuwLmuCz\">\u4f7f\u7528\u7d22\u5f15\u4f86\u52a0\u901f\u67e5\u8a62<\/h2>\n<p>\u7d22\u5f15\u662f\u63d0\u9ad8\u6578\u64da\u5eab\u67e5\u8a62\u6027\u80fd\u7684\u95dc\u9375\u5de5\u5177\u3002\u901a\u904e\u5728\u8868\u7684\u67d0\u4e9b\u5217\u4e0a\u5275\u5efa\u7d22\u5f15\uff0c\u53ef\u4ee5\u986f\u8457\u6e1b\u5c11\u67e5\u8a62\u6240\u9700\u7684\u6642\u9593\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u4f7f\u7528\u7d22\u5f15\u7684\u6700\u4f73\u5be6\u8e10\uff1a<\/p>\n<ul>\n<li><strong>\u9078\u64c7\u5408\u9069\u7684\u5217\uff1a<\/strong>\u901a\u5e38\uff0c\u7d93\u5e38\u7528\u65bc\u67e5\u8a62\u689d\u4ef6\uff08WHERE\u5b50\u53e5\uff09\u3001\u6392\u5e8f\uff08ORDER BY\uff09\u6216\u5206\u7d44\uff08GROUP BY\uff09\u7684\u5217\u61c9\u8a72\u8003\u616e\u5efa\u7acb\u7d22\u5f15\u3002<\/li>\n<li><strong>\u907f\u514d\u904e\u591a\u7d22\u5f15\uff1a<\/strong>\u96d6\u7136\u7d22\u5f15\u53ef\u4ee5\u52a0\u901f\u67e5\u8a62\uff0c\u4f46\u904e\u591a\u7684\u7d22\u5f15\u6703\u5f71\u97ff\u6578\u64da\u63d2\u5165\u3001\u66f4\u65b0\u548c\u522a\u9664\u7684\u6027\u80fd\u3002\u56e0\u6b64\uff0c\u61c9\u8a72\u6839\u64da\u5be6\u969b\u9700\u6c42\u4f86\u9078\u64c7\u7d22\u5f15\u3002<\/li>\n<li><strong>\u4f7f\u7528\u8907\u5408\u7d22\u5f15\uff1a<\/strong>\u5c0d\u65bc\u7d93\u5e38\u4e00\u8d77\u51fa\u73fe\u7684\u591a\u500b\u5217\uff0c\u53ef\u4ee5\u8003\u616e\u4f7f\u7528\u8907\u5408\u7d22\u5f15\uff0c\u9019\u6a23\u53ef\u4ee5\u9032\u4e00\u6b65\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u3002<\/li>\n<\/ul>\n<pre><code>-- \u5275\u5efa\u55ae\u5217\u7d22\u5f15\nCREATE INDEX idx_name ON users(name);\n\n-- \u5275\u5efa\u8907\u5408\u7d22\u5f15\nCREATE INDEX idx_name_age ON users(name, age);\n<\/code><\/pre>\n<h2 id=\"%e9%81%bf%e5%85%8d%e4%bd%bf%e7%94%a8select-cVCuwLmuCz\">\u907f\u514d\u4f7f\u7528SELECT *<\/h2>\n<p>\u5728SQL\u67e5\u8a62\u4e2d\uff0c\u4f7f\u7528SELECT *\u6703\u5c0e\u81f4\u6578\u64da\u5eab\u8fd4\u56de\u6240\u6709\u5217\u7684\u6578\u64da\uff0c\u9019\u6a23\u4e0d\u50c5\u6d6a\u8cbb\u4e86\u5e36\u5bec\uff0c\u9084\u53ef\u80fd\u5f71\u97ff\u6027\u80fd\u3002\u6700\u4f73\u505a\u6cd5\u662f\u50c5\u9078\u64c7\u9700\u8981\u7684\u5217\uff0c\u9019\u6a23\u53ef\u4ee5\u6e1b\u5c11\u6578\u64da\u7684\u50b3\u8f38\u91cf\u3002<\/p>\n<pre><code>-- \u4e0d\u5efa\u8b70\u7684\u5beb\u6cd5\nSELECT * FROM users WHERE age &gt; 30;\n\n-- \u5efa\u8b70\u7684\u5beb\u6cd5\nSELECT name, email FROM users WHERE age &gt; 30;\n<\/code><\/pre>\n<h2 id=\"%e4%bd%bf%e7%94%a8join%e8%80%8c%e9%9d%9e%e5%ad%90%e6%9f%a5%e8%a9%a2-cVCuwLmuCz\">\u4f7f\u7528JOIN\u800c\u975e\u5b50\u67e5\u8a62<\/h2>\n<p>\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u4f7f\u7528JOIN\u64cd\u4f5c\u6bd4\u4f7f\u7528\u5b50\u67e5\u8a62\u66f4\u6709\u6548\u7387\u3002\u5b50\u67e5\u8a62\u53ef\u80fd\u6703\u5c0e\u81f4\u591a\u6b21\u67e5\u8a62\uff0c\u800cJOIN\u5247\u53ef\u4ee5\u5728\u4e00\u6b21\u67e5\u8a62\u4e2d\u7372\u53d6\u6240\u9700\u7684\u6578\u64da\u3002\u4ee5\u4e0b\u662f\u793a\u4f8b\uff1a<\/p>\n<pre><code>-- \u4f7f\u7528\u5b50\u67e5\u8a62\nSELECT name FROM users WHERE id IN (SELECT user_id FROM orders WHERE amount &gt; 100);\n\n-- \u4f7f\u7528JOIN\nSELECT u.name FROM users u JOIN orders o ON u.id = o.user_id WHERE o.amount &gt; 100;\n<\/code><\/pre>\n<h2 id=\"%e9%81%a9%e7%95%b6%e4%bd%bf%e7%94%a8limit%e5%92%8coffset-cVCuwLmuCz\">\u9069\u7576\u4f7f\u7528LIMIT\u548cOFFSET<\/h2>\n<p>\u5728\u8655\u7406\u5927\u91cf\u6578\u64da\u6642\uff0c\u4f7f\u7528LIMIT\u548cOFFSET\u53ef\u4ee5\u6709\u6548\u5730\u63a7\u5236\u67e5\u8a62\u8fd4\u56de\u7684\u6578\u64da\u91cf\uff0c\u5f9e\u800c\u63d0\u9ad8\u6027\u80fd\u3002\u9019\u5728\u5be6\u73fe\u5206\u9801\u529f\u80fd\u6642\u7279\u5225\u6709\u7528\u3002<\/p>\n<pre><code>-- \u7372\u53d6\u524d10\u689d\u8a18\u9304\nSELECT * FROM users LIMIT 10;\n\n-- \u7372\u53d6\u7b2c11\u523020\u689d\u8a18\u9304\nSELECT * FROM users LIMIT 10 OFFSET 10;\n<\/code><\/pre>\n<h2 id=\"%e5%ae%9a%e6%9c%9f%e5%88%86%e6%9e%90%e5%92%8c%e5%84%aa%e5%8c%96%e6%9f%a5%e8%a9%a2%e8%a8%88%e5%8a%83-cVCuwLmuCz\">\u5b9a\u671f\u5206\u6790\u548c\u512a\u5316\u67e5\u8a62\u8a08\u5283<\/h2>\n<p>\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u901a\u5e38\u63d0\u4f9b\u5de5\u5177\u4f86\u5206\u6790\u67e5\u8a62\u8a08\u5283\uff0c\u9019\u4e9b\u5de5\u5177\u53ef\u4ee5\u5e6b\u52a9\u958b\u767c\u8005\u4e86\u89e3\u67e5\u8a62\u7684\u57f7\u884c\u65b9\u5f0f\u3002\u901a\u904e\u5206\u6790\u67e5\u8a62\u8a08\u5283\uff0c\u53ef\u4ee5\u8b58\u5225\u6027\u80fd\u74f6\u9838\u4e26\u9032\u884c\u76f8\u61c9\u7684\u512a\u5316\u3002<\/p>\n<pre><code>-- \u5728MySQL\u4e2d\u4f7f\u7528EXPLAIN\u4f86\u5206\u6790\u67e5\u8a62\u8a08\u5283\nEXPLAIN SELECT name FROM users WHERE age &gt; 30;\n<\/code><\/pre>\n<h2 id=\"%e7%b5%90%e8%ab%96-cVCuwLmuCz\">\u7d50\u8ad6<\/h2>\n<p>SQL\u8a9e\u53e5\u7684\u512a\u5316\u662f\u63d0\u5347\u6578\u64da\u5eab\u6027\u80fd\u7684\u91cd\u8981\u6b65\u9a5f\u3002\u901a\u904e\u5408\u7406\u4f7f\u7528\u7d22\u5f15\u3001\u907f\u514d\u4e0d\u5fc5\u8981\u7684\u67e5\u8a62\u3001\u9078\u64c7\u5408\u9069\u7684\u67e5\u8a62\u65b9\u5f0f\u4ee5\u53ca\u5b9a\u671f\u5206\u6790\u67e5\u8a62\u8a08\u5283\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u986f\u8457\u63d0\u9ad8\u6578\u64da\u5eab\u7684\u6548\u7387\u3002\u9019\u4e9b\u512a\u5316\u7b56\u7565\u4e0d\u50c5\u80fd\u5920\u63d0\u5347\u61c9\u7528\u7a0b\u5e8f\u7684\u97ff\u61c9\u901f\u5ea6\uff0c\u9084\u80fd\u6539\u5584\u7528\u6236\u9ad4\u9a57\u3002<\/p>\n<p>\u5982\u9700\u9032\u4e00\u6b65\u4e86\u89e3\u5982\u4f55\u5728\u60a8\u7684\u9805\u76ee\u4e2d\u5be6\u65bd\u9019\u4e9b\u512a\u5316\u7b56\u7565\uff0c\u6216\u5c0b\u627e\u5408\u9069\u7684 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0c\u8acb\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4ee5\u7372\u53d6\u66f4\u591a\u4fe1\u606f\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u63a2\u7d22\u6578\u64da\u5eab\u6027\u80fd\u512a\u5316\u7684SQL\u8a9e\u53e5\u512a\u5316\u6280\u5de7\uff0c\u63d0\u5347\u67e5\u8a62\u6548\u7387\uff0c\u6e1b\u5c11\u8cc7\u6e90\u6d88\u8017\uff0c\u5be6\u73fe\u66f4\u5feb\u7684\u6578\u64da\u8655\u7406\u3002<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-187478","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/187478","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=187478"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/187478\/revisions"}],"predecessor-version":[{"id":187479,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/187478\/revisions\/187479"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=187478"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=187478"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=187478"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}