{"id":74789,"date":"2024-10-15T22:54:14","date_gmt":"2024-10-15T14:54:14","guid":{"rendered":"https:\/\/server.hk\/cnblog\/74789\/"},"modified":"2024-10-15T22:54:14","modified_gmt":"2024-10-15T14:54:14","slug":"mysql-select%e4%bd%bf%e7%94%a8%e6%8a%80%e5%b7%a7%e5%a4%a7%e5%85%a8","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/74789\/","title":{"rendered":"MySQL SELECT\u4f7f\u7528\u6280\u5de7\u5927\u5168"},"content":{"rendered":"<h1 id=\"mysql-select%e4%bd%bf%e7%94%a8%e6%8a%80%e5%b7%a7%e5%a4%a7%e5%85%a8-CZdZoElSpN\">MySQL SELECT\u4f7f\u7528\u6280\u5de7\u5927\u5168<\/h1>\n<p>MySQL\u662f\u4e00\u7a2e\u6d41\u884c\u7684\u95dc\u806f\u5f0f\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\uff0c\u5ee3\u6cdb\u61c9\u7528\u65bc\u5404\u7a2e\u7db2\u7ad9\u548c\u61c9\u7528\u7a0b\u5e8f\u4e2d\u3002SELECT\u8a9e\u53e5\u662fMySQL\u4e2d\u6700\u5e38\u7528\u7684\u67e5\u8a62\u8a9e\u53e5\u4e4b\u4e00\uff0c\u80fd\u5920\u5f9e\u6578\u64da\u5eab\u4e2d\u6aa2\u7d22\u6578\u64da\u3002\u672c\u6587\u5c07\u4ecb\u7d39\u4e00\u4e9bMySQL SELECT\u8a9e\u53e5\u7684\u4f7f\u7528\u6280\u5de7\uff0c\u5e6b\u52a9\u958b\u767c\u8005\u66f4\u6709\u6548\u5730\u9032\u884c\u6578\u64da\u67e5\u8a62\u3002<\/p>\n<h2 id=\"%e5%9f%ba%e6%9c%acselect%e8%aa%9e%e5%8f%a5-CZdZoElSpN\">\u57fa\u672cSELECT\u8a9e\u53e5<\/h2>\n<p>\u6700\u57fa\u672c\u7684SELECT\u8a9e\u53e5\u683c\u5f0f\u5982\u4e0b\uff1a<\/p>\n<pre><code>SELECT column1, column2 FROM table_name;<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u82e5\u8981\u5f9e\u540d\u70ba\u201cusers\u201d\u7684\u8868\u4e2d\u9078\u64c7\u201cusername\u201d\u548c\u201cemail\u201d\u5169\u500b\u5b57\u6bb5\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u8a9e\u53e5\uff1a<\/p>\n<pre><code>SELECT username, email FROM users;<\/code><\/pre>\n<h2 id=\"%e4%bd%bf%e7%94%a8where%e6%a2%9d%e4%bb%b6%e9%81%8e%e6%bf%be%e6%95%b8%e6%93%9a-CZdZoElSpN\">\u4f7f\u7528WHERE\u689d\u4ef6\u904e\u6ffe\u6578\u64da<\/h2>\n<p>\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528WHERE\u5b50\u53e5\u53ef\u4ee5\u904e\u6ffe\u51fa\u7b26\u5408\u7279\u5b9a\u689d\u4ef6\u7684\u6578\u64da\u3002\u4f8b\u5982\uff0c\u82e5\u8981\u67e5\u8a62\u5e74\u9f61\u5927\u65bc30\u7684\u7528\u6236\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>SELECT * FROM users WHERE age &gt; 30;<\/code><\/pre>\n<h2 id=\"%e6%8e%92%e5%ba%8f%e7%b5%90%e6%9e%9c-CZdZoElSpN\">\u6392\u5e8f\u7d50\u679c<\/h2>\n<p>\u4f7f\u7528ORDER BY\u5b50\u53e5\u53ef\u4ee5\u5c0d\u67e5\u8a62\u7d50\u679c\u9032\u884c\u6392\u5e8f\u3002\u53ef\u4ee5\u9078\u64c7\u5347\u5e8f\uff08ASC\uff09\u6216\u964d\u5e8f\uff08DESC\uff09\u3002\u4f8b\u5982\uff0c\u82e5\u8981\u6309\u5e74\u9f61\u5347\u5e8f\u6392\u5217\u7528\u6236\uff0c\u53ef\u4ee5\u4f7f\u7528\uff1a<\/p>\n<pre><code>SELECT * FROM users ORDER BY age ASC;<\/code><\/pre>\n<h2 id=\"%e9%99%90%e5%88%b6%e6%9f%a5%e8%a9%a2%e7%b5%90%e6%9e%9c%e6%95%b8%e9%87%8f-CZdZoElSpN\">\u9650\u5236\u67e5\u8a62\u7d50\u679c\u6578\u91cf<\/h2>\n<p>\u4f7f\u7528LIMIT\u5b50\u53e5\u53ef\u4ee5\u9650\u5236\u67e5\u8a62\u7d50\u679c\u7684\u6578\u91cf\u3002\u4f8b\u5982\uff0c\u82e5\u53ea\u60f3\u7372\u53d6\u524d5\u689d\u8a18\u9304\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>SELECT * FROM users LIMIT 5;<\/code><\/pre>\n<h2 id=\"%e4%bd%bf%e7%94%a8join%e9%80%a3%e6%8e%a5%e5%a4%9a%e5%80%8b%e8%a1%a8-CZdZoElSpN\">\u4f7f\u7528JOIN\u9023\u63a5\u591a\u500b\u8868<\/h2>\n<p>\u5728\u6578\u64da\u5eab\u4e2d\uff0c\u7d93\u5e38\u9700\u8981\u5f9e\u591a\u500b\u8868\u4e2d\u6aa2\u7d22\u6578\u64da\u3002JOIN\u5b50\u53e5\u53ef\u4ee5\u7528\u4f86\u9023\u63a5\u9019\u4e9b\u8868\u3002\u4f8b\u5982\uff0c\u82e5\u8981\u5f9e\u201cusers\u201d\u548c\u201corders\u201d\u8868\u4e2d\u67e5\u8a62\u7528\u6236\u53ca\u5176\u8a02\u55ae\u4fe1\u606f\uff0c\u53ef\u4ee5\u4f7f\u7528INNER JOIN\uff1a<\/p>\n<pre><code>SELECT users.username, orders.order_id \nFROM users \nINNER JOIN orders ON users.id = orders.user_id;<\/code><\/pre>\n<h2 id=\"%e4%bd%bf%e7%94%a8group-by%e9%80%b2%e8%a1%8c%e5%88%86%e7%b5%84-CZdZoElSpN\">\u4f7f\u7528GROUP BY\u9032\u884c\u5206\u7d44<\/h2>\n<p>GROUP BY\u5b50\u53e5\u53ef\u4ee5\u5c07\u67e5\u8a62\u7d50\u679c\u6309\u67d0\u4e00\u5b57\u6bb5\u9032\u884c\u5206\u7d44\uff0c\u4e26\u53ef\u8207\u805a\u5408\u51fd\u6578\uff08\u5982COUNT\u3001SUM\u7b49\uff09\u4e00\u8d77\u4f7f\u7528\u3002\u4f8b\u5982\uff0c\u82e5\u8981\u67e5\u8a62\u6bcf\u500b\u5e74\u9f61\u6bb5\u7684\u7528\u6236\u6578\u91cf\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>SELECT age, COUNT(*) \nFROM users \nGROUP BY age;<\/code><\/pre>\n<h2 id=\"%e4%bd%bf%e7%94%a8having%e9%81%8e%e6%bf%be%e5%88%86%e7%b5%84%e7%b5%90%e6%9e%9c-CZdZoElSpN\">\u4f7f\u7528HAVING\u904e\u6ffe\u5206\u7d44\u7d50\u679c<\/h2>\n<p>HAVING\u5b50\u53e5\u7528\u65bc\u904e\u6ffeGROUP BY\u7684\u7d50\u679c\u3002\u4f8b\u5982\uff0c\u82e5\u8981\u67e5\u8a62\u5e74\u9f61\u5927\u65bc30\u7684\u7528\u6236\u6578\u91cf\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>SELECT age, COUNT(*) \nFROM users \nGROUP BY age \nHAVING age &gt; 30;<\/code><\/pre>\n<h2 id=\"%e4%bd%bf%e7%94%a8%e5%ad%90%e6%9f%a5%e8%a9%a2-CZdZoElSpN\">\u4f7f\u7528\u5b50\u67e5\u8a62<\/h2>\n<p>\u5b50\u67e5\u8a62\u662f\u6307\u5728\u4e00\u500b\u67e5\u8a62\u4e2d\u5d4c\u5957\u53e6\u4e00\u500b\u67e5\u8a62\u3002\u9019\u5728\u9700\u8981\u6839\u64da\u5176\u4ed6\u67e5\u8a62\u7684\u7d50\u679c\u9032\u884c\u904e\u6ffe\u6642\u975e\u5e38\u6709\u7528\u3002\u4f8b\u5982\uff0c\u82e5\u8981\u67e5\u8a62\u6240\u6709\u4e0b\u904e\u8a02\u55ae\u7684\u7528\u6236\uff0c\u53ef\u4ee5\u4f7f\u7528\uff1a<\/p>\n<pre><code>SELECT * \nFROM users \nWHERE id IN (SELECT user_id FROM orders);<\/code><\/pre>\n<h2 id=\"%e7%b5%90%e8%ab%96-CZdZoElSpN\">\u7d50\u8ad6<\/h2>\n<p>MySQL\u7684SELECT\u8a9e\u53e5\u529f\u80fd\u5f37\u5927\uff0c\u9748\u6d3b\u904b\u7528\u5404\u7a2e\u5b50\u53e5\u548c\u6280\u5de7\u53ef\u4ee5\u5927\u5927\u63d0\u9ad8\u6578\u64da\u67e5\u8a62\u7684\u6548\u7387\u3002\u7121\u8ad6\u662f\u57fa\u672c\u67e5\u8a62\u3001\u689d\u4ef6\u904e\u6ffe\u3001\u6392\u5e8f\u9084\u662f\u591a\u8868\u9023\u63a5\uff0c\u638c\u63e1\u9019\u4e9b\u6280\u5de7\u90fd\u80fd\u5e6b\u52a9\u958b\u767c\u8005\u66f4\u597d\u5730\u7ba1\u7406\u548c\u5206\u6790\u6578\u64da\u3002<\/p>\n<p>\u5982\u9700\u9032\u4e00\u6b65\u4e86\u89e3\u5982\u4f55\u5728\u60a8\u7684\u9805\u76ee\u4e2d\u4f7f\u7528MySQL\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>Discover essential MySQL SELECT tips and tricks to enhance your database queries, optimize performance, and streamline data retrieval effectively.<\/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-74789","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/74789","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=74789"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/74789\/revisions"}],"predecessor-version":[{"id":74790,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/74789\/revisions\/74790"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=74789"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=74789"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=74789"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}