{"id":200917,"date":"2025-05-06T08:55:50","date_gmt":"2025-05-06T00:55:50","guid":{"rendered":"https:\/\/server.hk\/cnblog\/200917\/"},"modified":"2025-05-06T08:55:50","modified_gmt":"2025-05-06T00:55:50","slug":"%e5%a6%82%e4%bd%95%e6%9f%a5%e8%af%a2%e4%b8%8d%e5%90%8c%e8%af%be%e7%a8%8b%e6%88%90%e7%bb%a9%e7%9b%b8%e5%90%8c%e7%9a%84%e5%ad%a6%e7%94%9f%e4%bf%a1%e6%81%af%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/200917\/","title":{"rendered":"\u5982\u4f55\u67e5\u8be2\u4e0d\u540c\u8bfe\u7a0b\u6210\u7ee9\u76f8\u540c\u7684\u5b66\u751f\u4fe1\u606f\uff1f"},"content":{"rendered":"<p><b><\/b> <\/p>\n<h1>\u5982\u4f55\u67e5\u8be2\u4e0d\u540c\u8bfe\u7a0b\u6210\u7ee9\u76f8\u540c\u7684\u5b66\u751f\u4fe1\u606f\uff1f<\/h1>\n<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.17golang.com\/uploads\/20241120\/1732111608673decf82f526.jpg\" class=\"aligncenter\"><\/p>\n<p><strong>\u4e0d\u540c\u8bfe\u7a0b\u6210\u7ee9\u76f8\u540c\u7684\u5b66\u751f\u67e5\u8be2<\/strong><\/p>\n<p>\u7ed9\u51fa\u7684\u9898\u76ee\u662f\u67e5\u8be2\u4e0d\u540c\u8bfe\u7a0b\u6210\u7ee9\u76f8\u540c\u7684\u5b66\u751f\u4fe1\u606f\uff0c\u5305\u62ec\u5b66\u751f\u7f16\u53f7 (sid)\u3001\u8bfe\u7a0b\u7f16\u53f7 (cid) \u548c\u5b66\u751f\u6210\u7ee9 (score)\u3002\u89e3\u51b3\u8be5\u95ee\u9898\u7684\u6838\u5fc3\u601d\u8def\u662f\u4f7f\u7528\u805a\u5408\u51fd\u6570 group_concat()\uff0c\u5c06\u76f8\u540c\u6210\u7ee9\u4e2d\u6709\u591a\u540d\u5b66\u751f\u7684 sid \u805a\u5408\u8d77\u6765\uff0c\u518d\u8fdb\u884c\u7b5b\u9009\u3002<\/p>\n<p><strong>\u5177\u4f53\u6b65\u9aa4\uff1a<\/strong><\/p>\n<ol>\n<li>\u6839\u636e cid \u548c score \u5bf9 sc \u8868\u8fdb\u884c\u5206\u7ec4\u3002<\/li>\n<li>\u4f7f\u7528 group_concat() \u51fd\u6570\u5c06\u6bcf\u4e2a\u7ec4\u4e2d\u7684 sid \u805a\u5408\u5728\u4e00\u8d77\uff0c\u4ee5\u9017\u53f7\u5206\u9694\u3002<\/li>\n<li>\u4f7f\u7528 having \u5b50\u53e5\u7b5b\u9009\u5177\u6709\u8d85\u8fc7\u4e00\u540d\u5b66\u751f\u7684\u7ec4\uff0c\u8fd9\u4e9b\u7ec4\u5c31\u662f\u6210\u7ee9\u76f8\u540c\u4f46\u5b66\u751f\u4e0d\u540c\u7684\u60c5\u51b5\u3002<\/li>\n<li>\u8fd4\u56de\u805a\u5408\u540e\u7684 group_concat(sid)\u3001cid \u548c score\u3002<\/li>\n<\/ol>\n<p><strong>sql \u67e5\u8be2\uff1a<\/strong><\/p>\n<pre>select\n    group_concat(sid order by sid) as sids,\n    cid,\n    score\nfrom\n    sc\ngroup by\n    cid, score\nhaving\n    count(1) &gt; 1;<\/pre>\n<p><strong>\u793a\u4f8b\u6570\u636e\uff1a<\/strong><\/p>\n<p>\u4ee5\u4e0b\u4e3a\u793a\u4f8b\u6570\u636e\uff0c\u5176\u4e2d\u4e24\u7ec4\u6210\u7ee9\u76f8\u540c\uff1a<\/p>\n<pre>create table sc (sid int, cid int, score decimal);\ninsert into sc values (1, 1, 80.0);\ninsert into sc values (3, 1, 80.0);\ninsert into sc values (2, 3, 80.0);\ninsert into sc values (3, 3, 80.0);<\/pre>\n<p><strong>\u67e5\u8be2\u7ed3\u679c\uff1a<\/strong><\/p>\n<pre>select\n    group_concat(sid order by sid) as sids,\n    cid,\n    score\nfrom\n    sc\ngroup by\n    cid, score\nhaving\n    count(1) &gt; 1;<\/pre>\n<table>\n<thead>\n<tr>\n<th>sids<\/th>\n<th>cid<\/th>\n<th>score<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>1, 3<\/td>\n<td>1<\/td>\n<td>80.0<\/td>\n<\/tr>\n<tr>\n<td>2, 3<\/td>\n<td>3<\/td>\n<td>80.0<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>\u4eca\u5929\u5173\u4e8e\u300a\u5982\u4f55\u67e5\u8be2\u4e0d\u540c\u8bfe\u7a0b\u6210\u7ee9\u76f8\u540c\u7684\u5b66\u751f\u4fe1\u606f\uff1f\u300b\u7684\u5185\u5bb9\u5c31\u4ecb\u7ecd\u5230\u8fd9\u91cc\u4e86\uff0c\u662f\u4e0d\u662f\u5b66\u8d77\u6765\u4e00\u76ee\u4e86\u7136\uff01\u60f3\u8981\u4e86\u89e3\u66f4\u591a\u5173\u4e8e\u7684\u5185\u5bb9\u8bf7\u5173\u6ce8\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\uff01<\/p>\n<dl>\n<dt>\n <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"<p>\u5982\u4f55\u67e5\u8be2\u4e0d\u540c\u8bfe\u7a0b\u6210\u7ee9\u76f8\u540c\u7684\u5b66\u751f\u4fe1&#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-200917","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200917","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"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=200917"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200917\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=200917"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=200917"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=200917"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}