{"id":190692,"date":"2024-11-12T14:42:19","date_gmt":"2024-11-12T06:42:19","guid":{"rendered":"https:\/\/server.hk\/cnblog\/190692\/"},"modified":"2024-11-12T14:42:20","modified_gmt":"2024-11-12T06:42:20","slug":"%e4%ba%94%e5%a4%a7%e6%ad%a5%e9%a9%9f%e5%8a%a0%e5%8d%81%e5%80%8b%e6%a1%88%e4%be%8b%ef%bc%8c%e5%a0%aa%e7%a8%b1sql%e5%84%aa%e5%8c%96%e8%90%ac%e8%83%bd%e5%85%ac%e5%bc%8f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/190692\/","title":{"rendered":"\u4e94\u5927\u6b65\u9a5f\u52a0\u5341\u500b\u6848\u4f8b\uff0c\u582a\u7a31SQL\u512a\u5316\u842c\u80fd\u516c\u5f0f"},"content":{"rendered":"<h1 id=\"%e4%ba%94%e5%a4%a7%e6%ad%a5%e9%a9%9f%e5%8a%a0%e5%8d%81%e5%80%8b%e6%a1%88%e4%be%8b%ef%bc%8c%e5%a0%aa%e7%a8%b1sql%e5%84%aa%e5%8c%96%e8%90%ac%e8%83%bd%e5%85%ac%e5%bc%8f-xsRboRktdO\">\u4e94\u5927\u6b65\u9a5f\u52a0\u5341\u500b\u6848\u4f8b\uff0c\u582a\u7a31SQL\u512a\u5316\u842c\u80fd\u516c\u5f0f<\/h1>\n<p>\u5728\u7576\u4eca\u6578\u64da\u9a45\u52d5\u7684\u4e16\u754c\u4e2d\uff0cSQL\uff08\u7d50\u69cb\u5316\u67e5\u8a62\u8a9e\u8a00\uff09\u662f\u8207\u6578\u64da\u5eab\u9032\u884c\u4ea4\u4e92\u7684\u4e3b\u8981\u5de5\u5177\u3002\u96a8\u8457\u6578\u64da\u91cf\u7684\u589e\u9577\uff0cSQL\u67e5\u8a62\u7684\u6027\u80fd\u512a\u5316\u8b8a\u5f97\u8d8a\u4f86\u8d8a\u91cd\u8981\u3002\u672c\u6587\u5c07\u4ecb\u7d39\u4e94\u5927\u6b65\u9a5f\u4ee5\u53ca\u5341\u500b\u5be6\u969b\u6848\u4f8b\uff0c\u5e6b\u52a9\u60a8\u638c\u63e1SQL\u512a\u5316\u7684\u842c\u80fd\u516c\u5f0f\u3002<\/p>\n<h2 id=\"%e7%ac%ac%e4%b8%80%e6%ad%a5%ef%bc%9a%e5%88%86%e6%9e%90%e6%9f%a5%e8%a9%a2%e6%80%a7%e8%83%bd-xsRboRktdO\">\u7b2c\u4e00\u6b65\uff1a\u5206\u6790\u67e5\u8a62\u6027\u80fd<\/h2>\n<p>\u5728\u9032\u884c\u4efb\u4f55\u512a\u5316\u4e4b\u524d\uff0c\u9996\u5148\u9700\u8981\u5206\u6790\u7576\u524d\u67e5\u8a62\u7684\u6027\u80fd\u3002\u4f7f\u7528\u6578\u64da\u5eab\u63d0\u4f9b\u7684\u6027\u80fd\u5206\u6790\u5de5\u5177\uff0c\u5982MySQL\u7684EXPLAIN\u547d\u4ee4\uff0c\u53ef\u4ee5\u5e6b\u52a9\u60a8\u4e86\u89e3\u67e5\u8a62\u7684\u57f7\u884c\u8a08\u5283\u3002<\/p>\n<pre><code>EXPLAIN SELECT * FROM users WHERE age &gt; 30;<\/code><\/pre>\n<p>\u9019\u689d\u547d\u4ee4\u5c07\u986f\u793a\u67e5\u8a62\u7684\u57f7\u884c\u8a08\u5283\uff0c\u5305\u62ec\u4f7f\u7528\u7684\u7d22\u5f15\u3001\u884c\u6578\u4f30\u7b97\u7b49\u4fe1\u606f\u3002\u901a\u904e\u9019\u4e9b\u6578\u64da\uff0c\u60a8\u53ef\u4ee5\u8b58\u5225\u51fa\u6027\u80fd\u74f6\u9838\u3002<\/p>\n<h2 id=\"%e7%ac%ac%e4%ba%8c%e6%ad%a5%ef%bc%9a%e5%84%aa%e5%8c%96%e7%b4%a2%e5%bc%95-xsRboRktdO\">\u7b2c\u4e8c\u6b65\uff1a\u512a\u5316\u7d22\u5f15<\/h2>\n<p>\u7d22\u5f15\u662f\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u7684\u95dc\u9375\u3002\u78ba\u4fdd\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528\u7684\u5217\u4e0a\u5efa\u7acb\u9069\u7576\u7684\u7d22\u5f15\u3002\u904e\u591a\u6216\u4e0d\u5fc5\u8981\u7684\u7d22\u5f15\u6703\u5f71\u97ff\u5beb\u5165\u6027\u80fd\uff0c\u56e0\u6b64\u9700\u8981\u5e73\u8861\u8b80\u53d6\u548c\u5beb\u5165\u7684\u9700\u6c42\u3002<\/p>\n<h3 id=\"%e6%a1%88%e4%be%8b1%ef%bc%9a%e4%bd%bf%e7%94%a8%e8%a4%87%e5%90%88%e7%b4%a2%e5%bc%95-xsRboRktdO\">\u6848\u4f8b1\uff1a\u4f7f\u7528\u8907\u5408\u7d22\u5f15<\/h3>\n<p>\u5047\u8a2d\u6709\u4e00\u500b\u67e5\u8a62\u9700\u8981\u540c\u6642\u6839\u64da\u7528\u6236\u7684\u5e74\u9f61\u548c\u57ce\u5e02\u9032\u884c\u7be9\u9078\uff1a<\/p>\n<pre><code>SELECT * FROM users WHERE age &gt; 30 AND city = 'Hong Kong';<\/code><\/pre>\n<p>\u5728\u9019\u7a2e\u60c5\u6cc1\u4e0b\uff0c\u5efa\u7acb\u4e00\u500b\u8907\u5408\u7d22\u5f15\uff08age, city\uff09\u5c07\u986f\u8457\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u3002<\/p>\n<h2 id=\"%e7%ac%ac%e4%b8%89%e6%ad%a5%ef%bc%9a%e9%81%bf%e5%85%8dselect-xsRboRktdO\">\u7b2c\u4e09\u6b65\uff1a\u907f\u514dSELECT *<\/h2>\n<p>\u4f7f\u7528SELECT *\u6703\u5c0e\u81f4\u4e0d\u5fc5\u8981\u7684\u6578\u64da\u50b3\u8f38\uff0c\u5f71\u97ff\u6027\u80fd\u3002\u61c9\u8a72\u660e\u78ba\u6307\u5b9a\u9700\u8981\u7684\u5217\u3002<\/p>\n<h3 id=\"%e6%a1%88%e4%be%8b2%ef%bc%9a%e6%98%8e%e7%a2%ba%e5%88%97%e9%81%b8%e6%93%87-xsRboRktdO\">\u6848\u4f8b2\uff1a\u660e\u78ba\u5217\u9078\u64c7<\/h3>\n<pre><code>SELECT id, name FROM users WHERE age &gt; 30;<\/code><\/pre>\n<p>\u9019\u6a23\u53ef\u4ee5\u6e1b\u5c11\u6578\u64da\u7684\u50b3\u8f38\u91cf\uff0c\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u3002<\/p>\n<h2 id=\"%e7%ac%ac%e5%9b%9b%e6%ad%a5%ef%bc%9a%e4%bd%bf%e7%94%a8join%e8%80%8c%e9%9d%9e%e5%ad%90%e6%9f%a5%e8%a9%a2-xsRboRktdO\">\u7b2c\u56db\u6b65\uff1a\u4f7f\u7528JOIN\u800c\u975e\u5b50\u67e5\u8a62<\/h2>\n<p>\u5728\u8a31\u591a\u60c5\u6cc1\u4e0b\uff0c\u4f7f\u7528JOIN\u64cd\u4f5c\u6bd4\u4f7f\u7528\u5b50\u67e5\u8a62\u66f4\u9ad8\u6548\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<\/p>\n<h3 id=\"%e6%a1%88%e4%be%8b3%ef%bc%9a%e4%bd%bf%e7%94%a8join-xsRboRktdO\">\u6848\u4f8b3\uff1a\u4f7f\u7528JOIN<\/h3>\n<pre><code>SELECT u.name, o.order_date FROM users u JOIN orders o ON u.id = o.user_id WHERE u.age &gt; 30;<\/code><\/pre>\n<p>\u9019\u6a23\u7684\u67e5\u8a62\u901a\u5e38\u6bd4\u4f7f\u7528\u5b50\u67e5\u8a62\u66f4\u5feb\u3002<\/p>\n<h2 id=\"%e7%ac%ac%e4%ba%94%e6%ad%a5%ef%bc%9a%e5%ae%9a%e6%9c%9f%e6%b8%85%e7%90%86%e6%95%b8%e6%93%9a-xsRboRktdO\">\u7b2c\u4e94\u6b65\uff1a\u5b9a\u671f\u6e05\u7406\u6578\u64da<\/h2>\n<p>\u96a8\u8457\u6642\u9593\u7684\u63a8\u79fb\uff0c\u6578\u64da\u5eab\u4e2d\u7684\u6578\u64da\u53ef\u80fd\u6703\u8b8a\u5f97\u5197\u9918\u6216\u904e\u6642\u3002\u5b9a\u671f\u6e05\u7406\u4e0d\u5fc5\u8981\u7684\u6578\u64da\u53ef\u4ee5\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u3002<\/p>\n<h3 id=\"%e6%a1%88%e4%be%8b4%ef%bc%9a%e5%88%aa%e9%99%a4%e9%81%8e%e6%9c%9f%e6%95%b8%e6%93%9a-xsRboRktdO\">\u6848\u4f8b4\uff1a\u522a\u9664\u904e\u671f\u6578\u64da<\/h3>\n<pre><code>DELETE FROM users WHERE last_login &lt; NOW() - INTERVAL 1 YEAR;<\/code><\/pre>\n<p>\u9019\u6a23\u53ef\u4ee5\u6e1b\u5c11\u6578\u64da\u5eab\u7684\u5927\u5c0f\uff0c\u5f9e\u800c\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u3002<\/p>\n<h2 id=\"%e5%85%b6%e4%bb%96%e5%84%aa%e5%8c%96%e6%a1%88%e4%be%8b-xsRboRktdO\">\u5176\u4ed6\u512a\u5316\u6848\u4f8b<\/h2>\n<ul>\n<li><strong>\u6848\u4f8b5\uff1a<\/strong>\u4f7f\u7528LIMIT\u9650\u5236\u8fd4\u56de\u7684\u884c\u6578\u3002<\/li>\n<pre><code>SELECT * FROM users LIMIT 10;<\/code><\/pre>\n<li><strong>\u6848\u4f8b6\uff1a<\/strong>\u4f7f\u7528GROUP BY\u6642\uff0c\u78ba\u4fdd\u6709\u9069\u7576\u7684\u7d22\u5f15\u3002<\/li>\n<pre><code>SELECT city, COUNT(*) FROM users GROUP BY city;<\/code><\/pre>\n<li><strong>\u6848\u4f8b7\uff1a<\/strong>\u907f\u514d\u5728WHERE\u5b50\u53e5\u4e2d\u4f7f\u7528\u51fd\u6578\uff0c\u9019\u6703\u5c0e\u81f4\u5168\u8868\u6383\u63cf\u3002<\/li>\n<li><strong>\u6848\u4f8b8\uff1a<\/strong>\u4f7f\u7528UNION ALL\u800c\u975eUNION\uff0c\u7576\u4e0d\u9700\u8981\u53bb\u91cd\u6642\u3002<\/li>\n<li><strong>\u6848\u4f8b9\uff1a<\/strong>\u5c0d\u65bc\u5927\u578b\u6578\u64da\u96c6\uff0c\u8003\u616e\u4f7f\u7528\u5206\u5340\u8868\u3002<\/li>\n<li><strong>\u6848\u4f8b10\uff1a<\/strong>\u5b9a\u671f\u66f4\u65b0\u7d71\u8a08\u4fe1\u606f\uff0c\u4ee5\u5e6b\u52a9\u67e5\u8a62\u512a\u5316\u5668\u505a\u51fa\u66f4\u597d\u7684\u6c7a\u7b56\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-xsRboRktdO\">\u7e3d\u7d50<\/h2>\n<p>SQL\u512a\u5316\u662f\u4e00\u500b\u6301\u7e8c\u7684\u904e\u7a0b\uff0c\u901a\u904e\u4e0a\u8ff0\u4e94\u5927\u6b65\u9a5f\u548c\u5341\u500b\u6848\u4f8b\uff0c\u60a8\u53ef\u4ee5\u6709\u6548\u5730\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u3002\u7121\u8ad6\u662f\u4f7f\u7528\u9069\u7576\u7684\u7d22\u5f15\u3001\u907f\u514d\u4e0d\u5fc5\u8981\u7684\u6578\u64da\u50b3\u8f38\uff0c\u9084\u662f\u5b9a\u671f\u6e05\u7406\u6578\u64da\uff0c\u9019\u4e9b\u90fd\u662f\u63d0\u5347\u6578\u64da\u5eab\u6027\u80fd\u7684\u6709\u6548\u65b9\u6cd5\u3002\u5982\u679c\u60a8\u9700\u8981\u66f4\u9ad8\u6548\u7684\u6578\u64da\u8655\u7406\uff0c\u8003\u616e\u4f7f\u7528<a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a>\u6216<a href=\"https:\/\/server.hk\">\u4e91\u670d\u52a1\u5668<\/a>\u4f86\u652f\u6301\u60a8\u7684\u696d\u52d9\u9700\u6c42\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u638c\u63e1\u4e94\u5927\u6b65\u9a5f\u8207\u5341\u500b\u5be6\u969b\u6848\u4f8b\uff0c\u8f15\u9b06\u63d0\u5347SQL\u6548\u80fd\uff0c\u8b93\u4f60\u7684\u6578\u64da\u67e5\u8a62\u66f4\u5feb\u901f\u3001\u6e96\u78ba\uff0c\u6210\u70ba\u512a\u5316\u9ad8\u624b\uff01<\/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-190692","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/190692","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=190692"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/190692\/revisions"}],"predecessor-version":[{"id":190693,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/190692\/revisions\/190693"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=190692"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=190692"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=190692"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}