{"id":186488,"date":"2024-11-11T06:20:21","date_gmt":"2024-11-10T22:20:21","guid":{"rendered":"https:\/\/server.hk\/cnblog\/186488\/"},"modified":"2024-11-11T06:20:22","modified_gmt":"2024-11-10T22:20:22","slug":"%e6%95%b8%e6%93%9a%e5%ba%ab%e5%a4%9a%e9%87%8d%e5%ad%97%e6%ae%b5%e6%b1%82%e5%b9%b3%e5%9d%87%e5%80%bc%e6%8a%80%e5%b7%a7%e5%88%86%e4%ba%ab%ef%bc%88%e6%95%b8%e6%93%9a%e5%ba%ab%e5%a4%9a%e5%80%8b%e5%ad%97","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/186488\/","title":{"rendered":"\u6578\u64da\u5eab\u591a\u91cd\u5b57\u6bb5\u6c42\u5e73\u5747\u503c\u6280\u5de7\u5206\u4eab\uff08\u6578\u64da\u5eab\u591a\u500b\u5b57\u6bb5\u600e\u9ebc\u6c42\u5e73\u5747\u503c\uff09"},"content":{"rendered":"<h1 id=\"%e6%95%b8%e6%93%9a%e5%ba%ab%e5%a4%9a%e9%87%8d%e5%ad%97%e6%ae%b5%e6%b1%82%e5%b9%b3%e5%9d%87%e5%80%bc%e6%8a%80%e5%b7%a7%e5%88%86%e4%ba%ab%ef%bc%88%e6%95%b8%e6%93%9a%e5%ba%ab%e5%a4%9a%e5%80%8b%e5%ad%97-tbsQZphXqt\">\u6578\u64da\u5eab\u591a\u91cd\u5b57\u6bb5\u6c42\u5e73\u5747\u503c\u6280\u5de7\u5206\u4eab\uff08\u6578\u64da\u5eab\u591a\u500b\u5b57\u6bb5\u600e\u9ebc\u6c42\u5e73\u5747\u503c\uff09<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\uff0c\u8a08\u7b97\u591a\u500b\u5b57\u6bb5\u7684\u5e73\u5747\u503c\u662f\u4e00\u500b\u5e38\u898b\u7684\u9700\u6c42\u3002\u7121\u8ad6\u662f\u5728\u5831\u544a\u751f\u6210\u3001\u6578\u64da\u5206\u6790\u9084\u662f\u696d\u52d9\u6c7a\u7b56\u4e2d\uff0c\u80fd\u5920\u6709\u6548\u5730\u5f9e\u591a\u500b\u6578\u64da\u5b57\u6bb5\u4e2d\u63d0\u53d6\u51fa\u6709\u610f\u7fa9\u7684\u5e73\u5747\u503c\u90fd\u662f\u81f3\u95dc\u91cd\u8981\u7684\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u5982\u4f55\u5728\u6578\u64da\u5eab\u4e2d\u8a08\u7b97\u591a\u91cd\u5b57\u6bb5\u7684\u5e73\u5747\u503c\uff0c\u4e26\u63d0\u4f9b\u4e00\u4e9b\u5be6\u7528\u7684\u6280\u5de7\u548c\u793a\u4f8b\u3002<\/p>\n<h2 id=\"%e7%90%86%e8%a7%a3%e5%b9%b3%e5%9d%87%e5%80%bc%e7%9a%84%e6%a6%82%e5%bf%b5-tbsQZphXqt\">\u7406\u89e3\u5e73\u5747\u503c\u7684\u6982\u5ff5<\/h2>\n<p>\u5e73\u5747\u503c\u662f\u7d71\u8a08\u5b78\u4e2d\u4e00\u500b\u57fa\u672c\u7684\u6982\u5ff5\uff0c\u901a\u5e38\u7528\u4f86\u8868\u793a\u4e00\u7d44\u6578\u64da\u7684\u4e2d\u5fc3\u8da8\u52e2\u3002\u5728\u6578\u64da\u5eab\u4e2d\uff0c\u5e73\u5747\u503c\u7684\u8a08\u7b97\u901a\u5e38\u6d89\u53ca\u5230\u6578\u5b57\u5b57\u6bb5\u7684\u52a0\u7e3d\u548c\u8a08\u6578\u3002\u5c0d\u65bc\u591a\u500b\u5b57\u6bb5\u7684\u5e73\u5747\u503c\u8a08\u7b97\uff0c\u6211\u5011\u9700\u8981\u8003\u616e\u5982\u4f55\u5c07\u9019\u4e9b\u5b57\u6bb5\u7684\u6578\u64da\u6574\u5408\u5728\u4e00\u8d77\u3002<\/p>\n<h2 id=\"sql%e4%b8%ad%e7%9a%84%e5%b9%b3%e5%9d%87%e5%80%bc%e8%a8%88%e7%ae%97-tbsQZphXqt\">SQL\u4e2d\u7684\u5e73\u5747\u503c\u8a08\u7b97<\/h2>\n<p>\u5728SQL\u4e2d\uff0c\u8a08\u7b97\u5e73\u5747\u503c\u901a\u5e38\u4f7f\u7528 <code>AVG()<\/code> \u51fd\u6578\u3002\u9019\u500b\u51fd\u6578\u53ef\u4ee5\u7528\u4f86\u8a08\u7b97\u55ae\u500b\u5b57\u6bb5\u7684\u5e73\u5747\u503c\uff0c\u4f46\u5982\u679c\u6211\u5011\u9700\u8981\u8a08\u7b97\u591a\u500b\u5b57\u6bb5\u7684\u5e73\u5747\u503c\uff0c\u5247\u9700\u8981\u4e00\u4e9b\u984d\u5916\u7684\u6b65\u9a5f\u3002<\/p>\n<h3 id=\"%e7%a4%ba%e4%be%8b%ef%bc%9a%e8%a8%88%e7%ae%97%e5%a4%9a%e5%80%8b%e5%ad%97%e6%ae%b5%e7%9a%84%e5%b9%b3%e5%9d%87%e5%80%bc-tbsQZphXqt\">\u793a\u4f8b\uff1a\u8a08\u7b97\u591a\u500b\u5b57\u6bb5\u7684\u5e73\u5747\u503c<\/h3>\n<p>\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba <code>students<\/code> \u7684\u8868\u683c\uff0c\u5176\u4e2d\u5305\u542b\u5b78\u751f\u7684\u6578\u5b78\u3001\u79d1\u5b78\u548c\u82f1\u8a9e\u6210\u7e3e\u3002\u8868\u683c\u7d50\u69cb\u5982\u4e0b\uff1a<\/p>\n<pre>\nCREATE TABLE students (\n    id INT PRIMARY KEY,\n    name VARCHAR(100),\n    math_score DECIMAL(5,2),\n    science_score DECIMAL(5,2),\n    english_score DECIMAL(5,2)\n);\n<\/pre>\n<p>\u5982\u679c\u6211\u5011\u60f3\u8981\u8a08\u7b97\u6bcf\u4f4d\u5b78\u751f\u7684\u4e09\u79d1\u6210\u7e3e\u7684\u5e73\u5747\u503c\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0bSQL\u67e5\u8a62\uff1a<\/p>\n<pre>\nSELECT \n    id, \n    name, \n    (math_score + science_score + english_score) \/ 3 AS average_score \nFROM \n    students;\n<\/pre>\n<p>\u9019\u500b\u67e5\u8a62\u5c07\u8fd4\u56de\u6bcf\u4f4d\u5b78\u751f\u7684ID\u3001\u59d3\u540d\u4ee5\u53ca\u4ed6\u5011\u4e09\u79d1\u6210\u7e3e\u7684\u5e73\u5747\u503c\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8case%e8%aa%9e%e5%8f%a5%e9%80%b2%e8%a1%8c%e6%a2%9d%e4%bb%b6%e8%a8%88%e7%ae%97-tbsQZphXqt\">\u4f7f\u7528CASE\u8a9e\u53e5\u9032\u884c\u689d\u4ef6\u8a08\u7b97<\/h2>\n<p>\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u6211\u5011\u53ef\u80fd\u53ea\u60f3\u8a08\u7b97\u7b26\u5408\u7279\u5b9a\u689d\u4ef6\u7684\u5b57\u6bb5\u7684\u5e73\u5747\u503c\u3002\u9019\u6642\u53ef\u4ee5\u4f7f\u7528 <code>CASE<\/code> \u8a9e\u53e5\u4f86\u9032\u884c\u689d\u4ef6\u8a08\u7b97\u3002\u4f8b\u5982\uff0c\u5982\u679c\u6211\u5011\u53ea\u60f3\u8a08\u7b97\u6578\u5b78\u548c\u79d1\u5b78\u6210\u7e3e\u7684\u5e73\u5747\u503c\uff0c\u7576\u82f1\u8a9e\u6210\u7e3e\u4e0d\u70ba\u96f6\u6642\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre>\nSELECT \n    id, \n    name, \n    (math_score + science_score) \/ \n    (CASE WHEN english_score != 0 THEN 2 ELSE 1 END) AS average_score \nFROM \n    students;\n<\/pre>\n<p>\u9019\u6a23\u7684\u67e5\u8a62\u80fd\u5920\u9748\u6d3b\u5730\u6839\u64da\u689d\u4ef6\u4f86\u8a08\u7b97\u5e73\u5747\u503c\uff0c\u907f\u514d\u4e86\u56e0\u70ba\u67d0\u4e9b\u5b57\u6bb5\u70ba\u96f6\u800c\u5c0e\u81f4\u7684\u8a08\u7b97\u932f\u8aa4\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8group-by%e9%80%b2%e8%a1%8c%e5%88%86%e7%b5%84%e8%a8%88%e7%ae%97-tbsQZphXqt\">\u4f7f\u7528GROUP BY\u9032\u884c\u5206\u7d44\u8a08\u7b97<\/h2>\n<p>\u5728\u8655\u7406\u5927\u91cf\u6578\u64da\u6642\uff0c\u53ef\u80fd\u9700\u8981\u6839\u64da\u67d0\u4e9b\u5b57\u6bb5\u9032\u884c\u5206\u7d44\u8a08\u7b97\u5e73\u5747\u503c\u3002\u9019\u6642\u53ef\u4ee5\u4f7f\u7528 <code>GROUP BY<\/code> \u8a9e\u53e5\u3002\u4f8b\u5982\uff0c\u5982\u679c\u6211\u5011\u60f3\u8981\u6839\u64da\u73ed\u7d1a\u4f86\u8a08\u7b97\u6bcf\u500b\u73ed\u7d1a\u7684\u5e73\u5747\u6210\u7e3e\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre>\nSELECT \n    class, \n    AVG((math_score + science_score + english_score) \/ 3) AS average_score \nFROM \n    students \nGROUP BY \n    class;\n<\/pre>\n<p>\u9019\u6a23\u7684\u67e5\u8a62\u5c07\u8fd4\u56de\u6bcf\u500b\u73ed\u7d1a\u7684\u5e73\u5747\u6210\u7e3e\uff0c\u5e6b\u52a9\u6211\u5011\u66f4\u597d\u5730\u4e86\u89e3\u4e0d\u540c\u73ed\u7d1a\u7684\u5b78\u7fd2\u60c5\u6cc1\u3002<\/p>\n<h2 id=\"%e7%b8%bd%e7%b5%90-tbsQZphXqt\">\u7e3d\u7d50<\/h2>\n<p>\u8a08\u7b97\u6578\u64da\u5eab\u4e2d\u591a\u91cd\u5b57\u6bb5\u7684\u5e73\u5747\u503c\u662f\u4e00\u9805\u91cd\u8981\u7684\u6280\u80fd\uff0c\u80fd\u5920\u5e6b\u52a9\u6211\u5011\u5f9e\u6578\u64da\u4e2d\u63d0\u53d6\u6709\u50f9\u503c\u7684\u4fe1\u606f\u3002\u901a\u904e\u4f7f\u7528SQL\u4e2d\u7684 <code>AVG()<\/code> \u51fd\u6578\u3001<code>CASE<\/code> \u8a9e\u53e5\u4ee5\u53ca <code>GROUP BY<\/code> \u8a9e\u53e5\uff0c\u6211\u5011\u53ef\u4ee5\u9748\u6d3b\u5730\u8a08\u7b97\u51fa\u6240\u9700\u7684\u5e73\u5747\u503c\u3002\u9019\u4e9b\u6280\u5de7\u4e0d\u50c5\u9069\u7528\u65bc\u5b78\u8853\u7814\u7a76\uff0c\u4e5f\u5728\u5546\u696d\u5206\u6790\u4e2d\u767c\u63ee\u8457\u91cd\u8981\u4f5c\u7528\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684\u6578\u64da\u5eab\u89e3\u6c7a\u65b9\u6848\uff0c\u8003\u616e\u4f7f\u7528<a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a>\u4f86\u652f\u6301\u60a8\u7684\u6578\u64da\u7ba1\u7406\u9700\u6c42\u3002\u7121\u8ad6\u662f\u6578\u64da\u5b58\u5132\u9084\u662f\u6578\u64da\u8655\u7406\uff0c\u9078\u64c7\u5408\u9069\u7684<a href=\"https:\/\/server.hk\">\u4f3a\u670d\u5668<\/a>\u90fd\u80fd\u63d0\u5347\u60a8\u7684\u5de5\u4f5c\u6548\u7387\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u63a2\u7d22\u6578\u64da\u5eab\u4e2d\u591a\u500b\u5b57\u6bb5\u6c42\u5e73\u5747\u503c\u7684\u6280\u5de7\uff0c\u63d0\u5347\u6578\u64da\u5206\u6790\u6548\u7387\uff0c\u7c21\u5316\u8a08\u7b97\u904e\u7a0b\uff0c\u52a9\u4f60\u8f15\u9b06\u638c\u63e1\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-186488","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/186488","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=186488"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/186488\/revisions"}],"predecessor-version":[{"id":186489,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/186488\/revisions\/186489"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=186488"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=186488"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=186488"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}