{"id":182680,"date":"2024-11-09T23:58:19","date_gmt":"2024-11-09T15:58:19","guid":{"rendered":"https:\/\/server.hk\/cnblog\/182680\/"},"modified":"2024-11-09T23:58:20","modified_gmt":"2024-11-09T15:58:20","slug":"%e5%af%a6%e4%be%8b%e6%bc%94%e7%a4%ba%ef%bc%9a%e6%95%b8%e6%93%9a%e5%ba%ab%e5%a6%82%e4%bd%95%e4%bd%bf%e7%94%a8%e5%ad%90%e6%9f%a5%e8%a9%a2%ef%bc%88%e6%95%b8%e6%93%9a%e5%ba%ab%e5%ad%90%e6%9f%a5%e8%a9%a2","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/182680\/","title":{"rendered":"\u5be6\u4f8b\u6f14\u793a\uff1a\u6578\u64da\u5eab\u5982\u4f55\u4f7f\u7528\u5b50\u67e5\u8a62\uff08\u6578\u64da\u5eab\u5b50\u67e5\u8a62\u4f8b\u5b50\uff09"},"content":{"rendered":"<h1 id=\"%e5%af%a6%e4%be%8b%e6%bc%94%e7%a4%ba%ef%bc%9a%e6%95%b8%e6%93%9a%e5%ba%ab%e5%a6%82%e4%bd%95%e4%bd%bf%e7%94%a8%e5%ad%90%e6%9f%a5%e8%a9%a2%ef%bc%88%e6%95%b8%e6%93%9a%e5%ba%ab%e5%ad%90%e6%9f%a5%e8%a9%a2-cHVIUCurIe\">\u5be6\u4f8b\u6f14\u793a\uff1a\u6578\u64da\u5eab\u5982\u4f55\u4f7f\u7528\u5b50\u67e5\u8a62\uff08\u6578\u64da\u5eab\u5b50\u67e5\u8a62\u4f8b\u5b50\uff09<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0c\u5b50\u67e5\u8a62\u662f\u4e00\u7a2e\u5f37\u5927\u7684\u67e5\u8a62\u5de5\u5177\uff0c\u80fd\u5920\u5e6b\u52a9\u7528\u6236\u5f9e\u6578\u64da\u5eab\u4e2d\u63d0\u53d6\u66f4\u70ba\u7cbe\u78ba\u7684\u4fe1\u606f\u3002\u5b50\u67e5\u8a62\u662f\u6307\u5728\u4e00\u500b\u67e5\u8a62\u4e2d\u5d4c\u5957\u53e6\u4e00\u500b\u67e5\u8a62\uff0c\u901a\u5e38\u7528\u65bc\u5f9e\u4e00\u500b\u8868\u4e2d\u9078\u64c7\u6578\u64da\uff0c\u4e26\u6839\u64da\u9019\u4e9b\u6578\u64da\u5728\u53e6\u4e00\u500b\u8868\u4e2d\u9032\u884c\u67e5\u8a62\u3002\u672c\u6587\u5c07\u901a\u904e\u5be6\u4f8b\u6f14\u793a\u5982\u4f55\u4f7f\u7528\u5b50\u67e5\u8a62\uff0c\u4e26\u63d0\u4f9b\u4e00\u4e9b\u5e38\u898b\u7684\u61c9\u7528\u5834\u666f\u3002<\/p>\n<h2 id=\"%e5%ad%90%e6%9f%a5%e8%a9%a2%e7%9a%84%e5%9f%ba%e6%9c%ac%e6%a6%82%e5%bf%b5-cHVIUCurIe\">\u5b50\u67e5\u8a62\u7684\u57fa\u672c\u6982\u5ff5<\/h2>\n<p>\u5b50\u67e5\u8a62\u53ef\u4ee5\u51fa\u73fe\u5728\u591a\u500b SQL \u8a9e\u53e5\u4e2d\uff0c\u5305\u62ec SELECT\u3001INSERT\u3001UPDATE \u548c DELETE\u3002\u5b83\u5011\u53ef\u4ee5\u653e\u5728 WHERE \u5b50\u53e5\u3001FROM \u5b50\u53e5\u6216 SELECT \u5b50\u53e5\u4e2d\u3002\u5b50\u67e5\u8a62\u7684\u7d50\u679c\u53ef\u4ee5\u662f\u55ae\u500b\u503c\u3001\u55ae\u5217\u6216\u591a\u5217\u6578\u64da\u3002<\/p>\n<h2 id=\"%e5%ad%90%e6%9f%a5%e8%a9%a2%e7%9a%84%e9%a1%9e%e5%9e%8b-cHVIUCurIe\">\u5b50\u67e5\u8a62\u7684\u985e\u578b<\/h2>\n<ul>\n<li><strong>\u55ae\u884c\u5b50\u67e5\u8a62\uff1a<\/strong>\u8fd4\u56de\u55ae\u500b\u503c\uff0c\u901a\u5e38\u7528\u65bc\u6bd4\u8f03\u64cd\u4f5c\u3002<\/li>\n<li><strong>\u591a\u884c\u5b50\u67e5\u8a62\uff1a<\/strong>\u8fd4\u56de\u591a\u500b\u503c\uff0c\u901a\u5e38\u7528\u65bc IN \u6216 EXISTS \u64cd\u4f5c\u3002<\/li>\n<li><strong>\u76f8\u95dc\u5b50\u67e5\u8a62\uff1a<\/strong>\u4f9d\u8cf4\u65bc\u5916\u90e8\u67e5\u8a62\u7684\u7d50\u679c\uff0c\u901a\u5e38\u5728 WHERE \u5b50\u53e5\u4e2d\u4f7f\u7528\u3002<\/li>\n<\/ul>\n<h2 id=\"%e5%af%a6%e4%be%8b%e6%bc%94%e7%a4%ba-cHVIUCurIe\">\u5be6\u4f8b\u6f14\u793a<\/h2>\n<h3 id=\"1-%e5%96%ae%e8%a1%8c%e5%ad%90%e6%9f%a5%e8%a9%a2-cHVIUCurIe\">1. \u55ae\u884c\u5b50\u67e5\u8a62<\/h3>\n<p>\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba <code>employees<\/code> \u7684\u8868\uff0c\u5305\u542b\u54e1\u5de5\u7684\u57fa\u672c\u4fe1\u606f\uff0c\u5305\u62ec <code>id<\/code>\u3001<code>name<\/code> \u548c <code>salary<\/code>\u3002\u6211\u5011\u60f3\u8981\u67e5\u8a62\u6240\u6709\u85aa\u6c34\u9ad8\u65bc\u516c\u53f8\u6700\u9ad8\u85aa\u6c34\u7684\u54e1\u5de5\u3002\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b SQL \u8a9e\u53e5\uff1a<\/p>\n<pre><code>SELECT * FROM employees\nWHERE salary &gt; (SELECT MAX(salary) FROM employees);<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u5167\u90e8\u7684\u5b50\u67e5\u8a62 <code>(SELECT MAX(salary) FROM employees)<\/code> \u8fd4\u56de\u516c\u53f8\u6700\u9ad8\u85aa\u6c34\uff0c\u5916\u90e8\u67e5\u8a62\u5247\u9078\u64c7\u6240\u6709\u85aa\u6c34\u9ad8\u65bc\u8a72\u503c\u7684\u54e1\u5de5\u3002<\/p>\n<h3 id=\"2-%e5%a4%9a%e8%a1%8c%e5%ad%90%e6%9f%a5%e8%a9%a2-cHVIUCurIe\">2. \u591a\u884c\u5b50\u67e5\u8a62<\/h3>\n<p>\u5982\u679c\u6211\u5011\u60f3\u8981\u67e5\u8a62\u6240\u6709\u5728\u67d0\u500b\u90e8\u9580\u5de5\u4f5c\u7684\u54e1\u5de5\uff0c\u4e26\u4e14\u8a72\u90e8\u9580\u7684\u540d\u7a31\u70ba &#8220;Sales&#8221;\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b SQL \u8a9e\u53e5\uff1a<\/p>\n<pre><code>SELECT * FROM employees\nWHERE department_id IN (SELECT id FROM departments WHERE name = 'Sales');<\/code><\/pre>\n<p>\u9019\u88e1\uff0c\u5167\u90e8\u7684\u5b50\u67e5\u8a62\u8fd4\u56de\u6240\u6709\u540d\u70ba &#8220;Sales&#8221; \u7684\u90e8\u9580\u7684 ID\uff0c\u5916\u90e8\u67e5\u8a62\u5247\u9078\u64c7\u6240\u6709\u5728\u9019\u4e9b\u90e8\u9580\u5de5\u4f5c\u7684\u54e1\u5de5\u3002<\/p>\n<h3 id=\"3-%e7%9b%b8%e9%97%9c%e5%ad%90%e6%9f%a5%e8%a9%a2-cHVIUCurIe\">3. \u76f8\u95dc\u5b50\u67e5\u8a62<\/h3>\n<p>\u5047\u8a2d\u6211\u5011\u60f3\u8981\u67e5\u8a62\u6bcf\u500b\u90e8\u9580\u4e2d\u85aa\u6c34\u9ad8\u65bc\u8a72\u90e8\u9580\u5e73\u5747\u85aa\u6c34\u7684\u54e1\u5de5\u3002\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b SQL \u8a9e\u53e5\uff1a<\/p>\n<pre><code>SELECT * FROM employees e\nWHERE salary &gt; (SELECT AVG(salary) FROM employees WHERE department_id = e.department_id);<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u5167\u90e8\u7684\u5b50\u67e5\u8a62\u4f9d\u8cf4\u65bc\u5916\u90e8\u67e5\u8a62\u7684 <code>department_id<\/code>\uff0c\u56e0\u6b64\u6bcf\u500b\u90e8\u9580\u7684\u5e73\u5747\u85aa\u6c34\u90fd\u6703\u88ab\u8a08\u7b97\u51fa\u4f86\uff0c\u7136\u5f8c\u8207\u8a72\u90e8\u9580\u7684\u54e1\u5de5\u85aa\u6c34\u9032\u884c\u6bd4\u8f03\u3002<\/p>\n<h2 id=\"%e5%ad%90%e6%9f%a5%e8%a9%a2%e7%9a%84%e5%84%aa%e7%bc%ba%e9%bb%9e-cHVIUCurIe\">\u5b50\u67e5\u8a62\u7684\u512a\u7f3a\u9ede<\/h2>\n<p>\u4f7f\u7528\u5b50\u67e5\u8a62\u7684\u512a\u9ede\u5305\u62ec\uff1a<\/p>\n<ul>\n<li>\u80fd\u5920\u7c21\u5316\u8907\u96dc\u67e5\u8a62\uff0c\u8b93 SQL \u8a9e\u53e5\u66f4\u5177\u53ef\u8b80\u6027\u3002<\/li>\n<li>\u53ef\u4ee5\u5728\u4e00\u500b\u67e5\u8a62\u4e2d\u5b8c\u6210\u591a\u500b\u64cd\u4f5c\uff0c\u6e1b\u5c11\u4e86\u9700\u8981\u57f7\u884c\u7684\u67e5\u8a62\u6b21\u6578\u3002<\/li>\n<\/ul>\n<p>\u7136\u800c\uff0c\u5b50\u67e5\u8a62\u4e5f\u6709\u5176\u7f3a\u9ede\uff1a<\/p>\n<ul>\n<li>\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u6027\u80fd\u53ef\u80fd\u4e0d\u5982\u806f\u63a5\uff08JOIN\uff09\u64cd\u4f5c\uff0c\u7279\u5225\u662f\u7576\u5b50\u67e5\u8a62\u8fd4\u56de\u5927\u91cf\u6578\u64da\u6642\u3002<\/li>\n<li>\u904e\u591a\u7684\u5d4c\u5957\u67e5\u8a62\u53ef\u80fd\u6703\u4f7f SQL \u8a9e\u53e5\u8b8a\u5f97\u96e3\u4ee5\u7dad\u8b77\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-cHVIUCurIe\">\u7e3d\u7d50<\/h2>\n<p>\u5b50\u67e5\u8a62\u662f\u4e00\u7a2e\u9748\u6d3b\u4e14\u5f37\u5927\u7684\u5de5\u5177\uff0c\u80fd\u5920\u5e6b\u52a9\u7528\u6236\u5f9e\u6578\u64da\u5eab\u4e2d\u63d0\u53d6\u6240\u9700\u7684\u4fe1\u606f\u3002\u901a\u904e\u672c\u6587\u7684\u5be6\u4f8b\u6f14\u793a\uff0c\u6211\u5011\u4e86\u89e3\u4e86\u5982\u4f55\u4f7f\u7528\u55ae\u884c\u5b50\u67e5\u8a62\u3001\u591a\u884c\u5b50\u67e5\u8a62\u548c\u76f8\u95dc\u5b50\u67e5\u8a62\u4f86\u89e3\u6c7a\u5be6\u969b\u554f\u984c\u3002\u5728\u9078\u64c7\u4f7f\u7528\u5b50\u67e5\u8a62\u6642\uff0c\u61c9\u6839\u64da\u5177\u9ad4\u60c5\u6cc1\u8003\u616e\u5176\u512a\u7f3a\u9ede\uff0c\u4ee5\u9054\u5230\u6700\u4f73\u7684\u67e5\u8a62\u6027\u80fd\u3002<\/p>\n<p>\u5982\u679c\u60a8\u5c0d\u65bc\u6578\u64da\u5eab\u7ba1\u7406\u6216\u5176\u4ed6\u6280\u8853\u554f\u984c\u6709\u8208\u8da3\uff0c\u6b61\u8fce\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4e86\u89e3\u66f4\u591a\u8cc7\u8a0a\uff0c\u7279\u5225\u662f\u6211\u5011\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u65b9\u6848\uff0c\u70ba\u60a8\u7684\u696d\u52d9\u63d0\u4f9b\u7a69\u5b9a\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u63a2\u7d22\u6578\u64da\u5eab\u5b50\u67e5\u8a62\u7684\u5be6\u4f8b\u6f14\u793a\uff0c\u4e86\u89e3\u5982\u4f55\u6709\u6548\u4f7f\u7528\u5b50\u67e5\u8a62\u63d0\u5347\u6578\u64da\u67e5\u8a62\u6548\u7387\u548c\u9748\u6d3b\u6027\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-182680","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/182680","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=182680"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/182680\/revisions"}],"predecessor-version":[{"id":182681,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/182680\/revisions\/182681"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=182680"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=182680"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=182680"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}