{"id":187792,"date":"2024-11-11T17:13:19","date_gmt":"2024-11-11T09:13:19","guid":{"rendered":"https:\/\/server.hk\/cnblog\/187792\/"},"modified":"2024-11-11T17:13:20","modified_gmt":"2024-11-11T09:13:20","slug":"%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e8%81%9a%e9%9b%86%e5%87%bd%e6%95%b8%e7%9a%84%e4%bd%9c%e7%94%a8%e5%8f%8a%e9%81%8b%e7%94%a8%e6%96%b9%e6%b3%95%e7%b0%a1%e4%bb%8b-%e6%95%b8%e6%93%9a%e5%ba%ab","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/187792\/","title":{"rendered":"\u6578\u64da\u5eab\u4e2d\u805a\u96c6\u51fd\u6578\u7684\u4f5c\u7528\u53ca\u904b\u7528\u65b9\u6cd5\u7c21\u4ecb (\u6578\u64da\u5eab \u805a\u96c6\u51fd\u6578)"},"content":{"rendered":"<h1 id=\"%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e8%81%9a%e9%9b%86%e5%87%bd%e6%95%b8%e7%9a%84%e4%bd%9c%e7%94%a8%e5%8f%8a%e9%81%8b%e7%94%a8%e6%96%b9%e6%b3%95%e7%b0%a1%e4%bb%8b-oVaeXaGvIX\">\u6578\u64da\u5eab\u4e2d\u805a\u96c6\u51fd\u6578\u7684\u4f5c\u7528\u53ca\u904b\u7528\u65b9\u6cd5\u7c21\u4ecb<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0c\u805a\u96c6\u51fd\u6578\u662f\u4e00\u7a2e\u975e\u5e38\u91cd\u8981\u7684\u5de5\u5177\uff0c\u80fd\u5920\u5e6b\u52a9\u7528\u6236\u5f9e\u5927\u91cf\u6578\u64da\u4e2d\u63d0\u53d6\u6709\u7528\u7684\u4fe1\u606f\u3002\u805a\u96c6\u51fd\u6578\u901a\u5e38\u7528\u65bc\u6578\u64da\u5206\u6790\u548c\u5831\u544a\u751f\u6210\uff0c\u80fd\u5920\u5c0d\u6578\u64da\u9032\u884c\u8a08\u7b97\u3001\u7d71\u8a08\u548c\u532f\u7e3d\u3002\u672c\u6587\u5c07\u4ecb\u7d39\u805a\u96c6\u51fd\u6578\u7684\u57fa\u672c\u6982\u5ff5\u3001\u5e38\u898b\u985e\u578b\u53ca\u5176\u5728\u5be6\u969b\u61c9\u7528\u4e2d\u7684\u904b\u7528\u65b9\u6cd5\u3002<\/p>\n<h2 id=\"%e8%81%9a%e9%9b%86%e5%87%bd%e6%95%b8%e7%9a%84%e5%9f%ba%e6%9c%ac%e6%a6%82%e5%bf%b5-oVaeXaGvIX\">\u805a\u96c6\u51fd\u6578\u7684\u57fa\u672c\u6982\u5ff5<\/h2>\n<p>\u805a\u96c6\u51fd\u6578\u662f\u6307\u5728\u4e00\u7d44\u503c\u4e0a\u9032\u884c\u8a08\u7b97\u4e26\u8fd4\u56de\u55ae\u4e00\u503c\u7684\u51fd\u6578\u3002\u9019\u4e9b\u51fd\u6578\u901a\u5e38\u7528\u65bc SQL \u67e5\u8a62\u4e2d\uff0c\u80fd\u5920\u5c0d\u6578\u64da\u9032\u884c\u532f\u7e3d\u548c\u5206\u6790\u3002\u805a\u96c6\u51fd\u6578\u7684\u4e3b\u8981\u7279\u9ede\u662f\u5b83\u5011\u80fd\u5920\u8655\u7406\u591a\u884c\u6578\u64da\u4e26\u8fd4\u56de\u4e00\u500b\u7d50\u679c\uff0c\u9019\u4f7f\u5f97\u5b83\u5011\u5728\u6578\u64da\u5206\u6790\u4e2d\u975e\u5e38\u6709\u7528\u3002<\/p>\n<h2 id=\"%e5%b8%b8%e8%a6%8b%e7%9a%84%e8%81%9a%e9%9b%86%e5%87%bd%e6%95%b8-oVaeXaGvIX\">\u5e38\u898b\u7684\u805a\u96c6\u51fd\u6578<\/h2>\n<p>\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684\u805a\u96c6\u51fd\u6578\uff1a<\/p>\n<ul>\n<li><strong>COUNT()<\/strong>\uff1a\u8a08\u7b97\u884c\u6578\u3002\u6b64\u51fd\u6578\u8fd4\u56de\u7b26\u5408\u689d\u4ef6\u7684\u884c\u6578\u3002<\/li>\n<li><strong>SUM()<\/strong>\uff1a\u8a08\u7b97\u7e3d\u548c\u3002\u6b64\u51fd\u6578\u8fd4\u56de\u6307\u5b9a\u5217\u7684\u6240\u6709\u503c\u7684\u7e3d\u548c\u3002<\/li>\n<li><strong>AVG()<\/strong>\uff1a\u8a08\u7b97\u5e73\u5747\u503c\u3002\u6b64\u51fd\u6578\u8fd4\u56de\u6307\u5b9a\u5217\u7684\u5e73\u5747\u503c\u3002<\/li>\n<li><strong>MIN()<\/strong>\uff1a\u67e5\u627e\u6700\u5c0f\u503c\u3002\u6b64\u51fd\u6578\u8fd4\u56de\u6307\u5b9a\u5217\u4e2d\u7684\u6700\u5c0f\u503c\u3002<\/li>\n<li><strong>MAX()<\/strong>\uff1a\u67e5\u627e\u6700\u5927\u503c\u3002\u6b64\u51fd\u6578\u8fd4\u56de\u6307\u5b9a\u5217\u4e2d\u7684\u6700\u5927\u503c\u3002<\/li>\n<\/ul>\n<h2 id=\"%e8%81%9a%e9%9b%86%e5%87%bd%e6%95%b8%e7%9a%84%e9%81%8b%e7%94%a8%e6%96%b9%e6%b3%95-oVaeXaGvIX\">\u805a\u96c6\u51fd\u6578\u7684\u904b\u7528\u65b9\u6cd5<\/h2>\n<p>\u805a\u96c6\u51fd\u6578\u7684\u4f7f\u7528\u901a\u5e38\u8207 SQL \u8a9e\u53e5\u7d50\u5408\uff0c\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684\u4f7f\u7528\u7bc4\u4f8b\uff1a<\/p>\n<h3 id=\"1-%e8%a8%88%e7%ae%97%e8%a1%8c%e6%95%b8-oVaeXaGvIX\">1. \u8a08\u7b97\u884c\u6578<\/h3>\n<pre><code>SELECT COUNT(*) FROM employees;<\/code><\/pre>\n<p>\u4e0a\u8ff0\u67e5\u8a62\u5c07\u8fd4\u56de employees \u8868\u4e2d\u7684\u6240\u6709\u884c\u6578\u3002<\/p>\n<h3 id=\"2-%e8%a8%88%e7%ae%97%e7%b8%bd%e5%92%8c-oVaeXaGvIX\">2. \u8a08\u7b97\u7e3d\u548c<\/h3>\n<pre><code>SELECT SUM(salary) FROM employees WHERE department = 'Sales';<\/code><\/pre>\n<p>\u9019\u689d\u67e5\u8a62\u5c07\u8fd4\u56de\u92b7\u552e\u90e8\u9580\u6240\u6709\u54e1\u5de5\u85aa\u8cc7\u7684\u7e3d\u548c\u3002<\/p>\n<h3 id=\"3-%e8%a8%88%e7%ae%97%e5%b9%b3%e5%9d%87%e5%80%bc-oVaeXaGvIX\">3. \u8a08\u7b97\u5e73\u5747\u503c<\/h3>\n<pre><code>SELECT AVG(salary) FROM employees;<\/code><\/pre>\n<p>\u9019\u689d\u67e5\u8a62\u5c07\u8fd4\u56de\u6240\u6709\u54e1\u5de5\u85aa\u8cc7\u7684\u5e73\u5747\u503c\u3002<\/p>\n<h3 id=\"4-%e6%9f%a5%e6%89%be%e6%9c%80%e5%b0%8f%e5%80%bc%e5%92%8c%e6%9c%80%e5%a4%a7%e5%80%bc-oVaeXaGvIX\">4. \u67e5\u627e\u6700\u5c0f\u503c\u548c\u6700\u5927\u503c<\/h3>\n<pre><code>SELECT MIN(salary) AS MinSalary, MAX(salary) AS MaxSalary FROM employees;<\/code><\/pre>\n<p>\u9019\u689d\u67e5\u8a62\u5c07\u8fd4\u56de\u6240\u6709\u54e1\u5de5\u85aa\u8cc7\u4e2d\u7684\u6700\u5c0f\u503c\u548c\u6700\u5927\u503c\u3002<\/p>\n<h2 id=\"%e8%81%9a%e9%9b%86%e5%87%bd%e6%95%b8%e7%9a%84%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-oVaeXaGvIX\">\u805a\u96c6\u51fd\u6578\u7684\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5728\u4f7f\u7528\u805a\u96c6\u51fd\u6578\u6642\uff0c\u6709\u5e7e\u500b\u6ce8\u610f\u4e8b\u9805\u9700\u8981\u8003\u616e\uff1a<\/p>\n<ul>\n<li>\u805a\u96c6\u51fd\u6578\u901a\u5e38\u8207 <code>GROUP BY<\/code> \u5b50\u53e5\u4e00\u8d77\u4f7f\u7528\uff0c\u4ee5\u4fbf\u5c0d\u6578\u64da\u9032\u884c\u5206\u7d44\u3002<\/li>\n<li>\u5728\u4f7f\u7528\u805a\u96c6\u51fd\u6578\u6642\uff0c\u82e5\u67e5\u8a62\u4e2d\u5305\u542b\u5176\u4ed6\u5217\uff0c\u5247\u5fc5\u9808\u4f7f\u7528 <code>GROUP BY<\/code> \u9032\u884c\u5206\u7d44\u3002<\/li>\n<li>\u805a\u96c6\u51fd\u6578\u4e0d\u6703\u8003\u616e NULL \u503c\uff0c\u9019\u610f\u5473\u8457 NULL \u503c\u4e0d\u6703\u88ab\u8a08\u7b97\u5728\u5167\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-oVaeXaGvIX\">\u7e3d\u7d50<\/h2>\n<p>\u805a\u96c6\u51fd\u6578\u5728\u6578\u64da\u5eab\u4e2d\u626e\u6f14\u8457\u81f3\u95dc\u91cd\u8981\u7684\u89d2\u8272\uff0c\u80fd\u5920\u5e6b\u52a9\u7528\u6236\u5feb\u901f\u7372\u53d6\u6709\u50f9\u503c\u7684\u4fe1\u606f\u3002\u7121\u8ad6\u662f\u5728\u6578\u64da\u5206\u6790\u9084\u662f\u5831\u544a\u751f\u6210\u4e2d\uff0c\u805a\u96c6\u51fd\u6578\u90fd\u80fd\u63d0\u4f9b\u5f37\u5927\u7684\u652f\u6301\u3002\u4e86\u89e3\u5982\u4f55\u6709\u6548\u5730\u4f7f\u7528\u9019\u4e9b\u51fd\u6578\uff0c\u5c07\u6709\u52a9\u65bc\u63d0\u5347\u6578\u64da\u8655\u7406\u7684\u6548\u7387\u548c\u6e96\u78ba\u6027\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u6eff\u8db3\u4e0d\u540c\u7528\u6236\u7684\u9700\u6c42\u3002\u7121\u8ad6\u662f\u6578\u64da\u5eab\u7ba1\u7406\u9084\u662f\u5176\u4ed6\u61c9\u7528\uff0c\u6211\u5011\u7684 <a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a> \u90fd\u80fd\u70ba\u60a8\u63d0\u4f9b\u7a69\u5b9a\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3\u6578\u64da\u5eab\u4e2d\u805a\u96c6\u51fd\u6578\u7684\u4f5c\u7528\u53ca\u904b\u7528\u65b9\u6cd5\uff0c\u63d0\u5347\u6578\u64da\u5206\u6790\u6548\u7387\uff0c\u52a9\u529b\u696d\u52d9\u6c7a\u7b56\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-187792","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/187792","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=187792"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/187792\/revisions"}],"predecessor-version":[{"id":187793,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/187792\/revisions\/187793"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=187792"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=187792"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=187792"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}