{"id":76026,"date":"2024-10-16T03:14:13","date_gmt":"2024-10-15T19:14:13","guid":{"rendered":"https:\/\/server.hk\/cnblog\/76026\/"},"modified":"2024-10-16T03:14:14","modified_gmt":"2024-10-15T19:14:14","slug":"mysql-%e6%8a%80%e5%b7%a7%ef%bc%9a%e5%bf%ab%e9%80%9f%e5%88%aa%e9%99%a4%e6%95%b8%e6%93%9a%e5%ba%ab%e9%87%8d%e8%a4%87%e6%95%b8%e6%93%9a-mysql%e5%88%aa%e9%99%a4%e6%95%b8%e6%93%9a%e5%ba%ab%e9%87%8d","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/76026\/","title":{"rendered":"MySQL \u6280\u5de7\uff1a\u5feb\u901f\u522a\u9664\u6578\u64da\u5eab\u91cd\u8907\u6578\u64da (MySQL\u522a\u9664\u6578\u64da\u5eab\u91cd\u8907\u6578\u64da)"},"content":{"rendered":"<h1 id=\"mysql-%e6%8a%80%e5%b7%a7%ef%bc%9a%e5%bf%ab%e9%80%9f%e5%88%aa%e9%99%a4%e6%95%b8%e6%93%9a%e5%ba%ab%e9%87%8d%e8%a4%87%e6%95%b8%e6%93%9a-VLmWpRVBgr\">MySQL \u6280\u5de7\uff1a\u5feb\u901f\u522a\u9664\u6578\u64da\u5eab\u91cd\u8907\u6578\u64da<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\uff0c\u91cd\u8907\u6578\u64da\u662f\u4e00\u500b\u5e38\u898b\u7684\u554f\u984c\uff0c\u5c24\u5176\u662f\u5728\u5927\u578b\u6578\u64da\u96c6\u7684\u60c5\u6cc1\u4e0b\u3002\u91cd\u8907\u6578\u64da\u4e0d\u50c5\u6703\u4f54\u7528\u5b58\u5132\u7a7a\u9593\uff0c\u9084\u53ef\u80fd\u5c0e\u81f4\u67e5\u8a62\u6548\u7387\u4e0b\u964d\u548c\u6578\u64da\u4e0d\u4e00\u81f4\u6027\u3002\u56e0\u6b64\uff0c\u5b78\u6703\u5982\u4f55\u5feb\u901f\u6709\u6548\u5730\u522a\u9664\u91cd\u8907\u6578\u64da\u662f\u6bcf\u4f4d\u6578\u64da\u5eab\u7ba1\u7406\u54e1\u5fc5\u5099\u7684\u6280\u80fd\u4e4b\u4e00\u3002\u672c\u6587\u5c07\u4ecb\u7d39\u5e7e\u7a2e\u5728 MySQL \u4e2d\u522a\u9664\u91cd\u8907\u6578\u64da\u7684\u6280\u5de7\u3002<\/p>\n<h2 id=\"%e7%90%86%e8%a7%a3%e9%87%8d%e8%a4%87%e6%95%b8%e6%93%9a-VLmWpRVBgr\">\u7406\u89e3\u91cd\u8907\u6578\u64da<\/h2>\n<p>\u91cd\u8907\u6578\u64da\u662f\u6307\u5728\u6578\u64da\u5eab\u4e2d\u5b58\u5728\u591a\u689d\u76f8\u540c\u7684\u8a18\u9304\u3002\u9019\u4e9b\u8a18\u9304\u53ef\u80fd\u662f\u7531\u65bc\u6578\u64da\u5c0e\u5165\u932f\u8aa4\u3001\u7528\u6236\u8f38\u5165\u932f\u8aa4\u6216\u5176\u4ed6\u539f\u56e0\u9020\u6210\u7684\u3002\u70ba\u4e86\u6709\u6548\u5730\u522a\u9664\u91cd\u8907\u6578\u64da\uff0c\u9996\u5148\u9700\u8981\u78ba\u5b9a\u54ea\u4e9b\u5b57\u6bb5\u662f\u7528\u4f86\u5224\u65b7\u91cd\u8907\u7684\u6a19\u6e96\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8-group-by-%e5%92%8c-having-%e5%ad%90%e5%8f%a5-VLmWpRVBgr\">\u4f7f\u7528 GROUP BY \u548c HAVING \u5b50\u53e5<\/h2>\n<p>\u4e00\u7a2e\u5e38\u898b\u7684\u65b9\u6cd5\u662f\u4f7f\u7528 <code>GROUP BY<\/code> \u548c <code>HAVING<\/code> \u5b50\u53e5\u4f86\u8b58\u5225\u91cd\u8907\u7684\u8a18\u9304\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u793a\u4f8b\uff0c\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba <code>users<\/code> \u7684\u8868\uff0c\u5176\u4e2d\u5305\u542b\u7528\u6236\u7684\u96fb\u5b50\u90f5\u4ef6\u5730\u5740\uff1a<\/p>\n<pre><code>SELECT email, COUNT(*) as count\nFROM users\nGROUP BY email\nHAVING count &gt; 1;<\/code><\/pre>\n<p>\u9019\u6bb5\u67e5\u8a62\u5c07\u8fd4\u56de\u6240\u6709\u91cd\u8907\u7684\u96fb\u5b50\u90f5\u4ef6\u5730\u5740\u53ca\u5176\u51fa\u73fe\u7684\u6b21\u6578\u3002\u63a5\u4e0b\u4f86\uff0c\u6211\u5011\u53ef\u4ee5\u4f7f\u7528\u9019\u4e9b\u4fe1\u606f\u4f86\u522a\u9664\u91cd\u8907\u7684\u8a18\u9304\u3002<\/p>\n<h2 id=\"%e5%88%aa%e9%99%a4%e9%87%8d%e8%a4%87%e6%95%b8%e6%93%9a-VLmWpRVBgr\">\u522a\u9664\u91cd\u8907\u6578\u64da<\/h2>\n<p>\u522a\u9664\u91cd\u8907\u6578\u64da\u7684\u5e38\u7528\u65b9\u6cd5\u662f\u4f7f\u7528 <code>DELETE<\/code> \u8a9e\u53e5\u7d50\u5408\u5b50\u67e5\u8a62\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u793a\u4f8b\uff0c\u5c55\u793a\u5982\u4f55\u522a\u9664\u91cd\u8907\u7684\u96fb\u5b50\u90f5\u4ef6\u5730\u5740\uff0c\u53ea\u4fdd\u7559\u6bcf\u500b\u96fb\u5b50\u90f5\u4ef6\u7684\u7b2c\u4e00\u689d\u8a18\u9304\uff1a<\/p>\n<pre><code>DELETE FROM users\nWHERE id NOT IN (\n    SELECT * FROM (\n        SELECT MIN(id) \n        FROM users \n        GROUP BY email\n    ) as temp\n);<\/code><\/pre>\n<p>\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u6211\u5011\u9996\u5148\u9078\u64c7\u6bcf\u500b\u96fb\u5b50\u90f5\u4ef6\u7684\u6700\u5c0f <code>id<\/code>\uff0c\u7136\u5f8c\u522a\u9664\u6240\u6709\u4e0d\u5728\u9019\u500b\u5217\u8868\u4e2d\u7684\u8a18\u9304\u3002\u9019\u6a23\u53ef\u4ee5\u78ba\u4fdd\u6bcf\u500b\u96fb\u5b50\u90f5\u4ef6\u5730\u5740\u53ea\u4fdd\u7559\u4e00\u689d\u8a18\u9304\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8-row_number-%e5%87%bd%e6%95%b8-VLmWpRVBgr\">\u4f7f\u7528 ROW_NUMBER() \u51fd\u6578<\/h2>\n<p>\u5982\u679c\u60a8\u4f7f\u7528\u7684\u662f MySQL 8.0 \u6216\u66f4\u9ad8\u7248\u672c\uff0c\u53ef\u4ee5\u5229\u7528 <code>ROW_NUMBER()<\/code> \u51fd\u6578\u4f86\u66f4\u65b9\u4fbf\u5730\u522a\u9664\u91cd\u8907\u6578\u64da\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u793a\u4f8b\uff1a<\/p>\n<pre><code>WITH cte AS (\n    SELECT *, ROW_NUMBER() OVER (PARTITION BY email ORDER BY id) as row_num\n    FROM users\n)\nDELETE FROM cte WHERE row_num &gt; 1;<\/code><\/pre>\n<p>\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u6211\u5011\u4f7f\u7528\u516c\u5171\u8868\u8868\u9054\u5f0f (CTE) \u4f86\u70ba\u6bcf\u500b\u96fb\u5b50\u90f5\u4ef6\u5206\u914d\u4e00\u500b\u884c\u865f\uff0c\u7136\u5f8c\u522a\u9664\u884c\u865f\u5927\u65bc 1 \u7684\u8a18\u9304\uff0c\u5f9e\u800c\u4fdd\u7559\u6bcf\u500b\u96fb\u5b50\u90f5\u4ef6\u7684\u7b2c\u4e00\u689d\u8a18\u9304\u3002<\/p>\n<h2 id=\"%e7%b8%bd%e7%b5%90-VLmWpRVBgr\">\u7e3d\u7d50<\/h2>\n<p>\u522a\u9664 MySQL \u6578\u64da\u5eab\u4e2d\u7684\u91cd\u8907\u6578\u64da\u662f\u4e00\u9805\u91cd\u8981\u7684\u6578\u64da\u7ba1\u7406\u4efb\u52d9\u3002\u901a\u904e\u4f7f\u7528 <code>GROUP BY<\/code> \u548c <code>HAVING<\/code> \u5b50\u53e5\u3001<code>DELETE<\/code> \u8a9e\u53e5\u7d50\u5408\u5b50\u67e5\u8a62\uff0c\u6216\u5229\u7528 <code>ROW_NUMBER()<\/code> \u51fd\u6578\uff0c\u60a8\u53ef\u4ee5\u6709\u6548\u5730\u6e05\u7406\u6578\u64da\u5eab\u4e2d\u7684\u91cd\u8907\u8a18\u9304\u3002\u9019\u4e0d\u50c5\u80fd\u63d0\u9ad8\u6578\u64da\u5eab\u7684\u6027\u80fd\uff0c\u9084\u80fd\u78ba\u4fdd\u6578\u64da\u7684\u4e00\u81f4\u6027\u548c\u6e96\u78ba\u6027\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u89e3\u6c7a\u65b9\u6848\u4f86\u7ba1\u7406\u60a8\u7684\u6578\u64da\u5eab\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u5e6b\u52a9\u60a8\u8f15\u9b06\u61c9\u5c0d\u5404\u7a2e\u6578\u64da\u7ba1\u7406\u6311\u6230\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5b78\u7fd2\u5982\u4f55\u5728MySQL\u4e2d\u5feb\u901f\u522a\u9664\u91cd\u8907\u6578\u64da\uff0c\u63d0\u5347\u6578\u64da\u5eab\u6027\u80fd\uff0c\u78ba\u4fdd\u6578\u64da\u7684\u552f\u4e00\u6027\u8207\u6e96\u78ba\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-76026","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/76026","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=76026"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/76026\/revisions"}],"predecessor-version":[{"id":76027,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/76026\/revisions\/76027"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=76026"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=76026"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=76026"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}