{"id":200462,"date":"2025-05-06T12:00:29","date_gmt":"2025-05-06T04:00:29","guid":{"rendered":"https:\/\/server.hk\/cnblog\/200462\/"},"modified":"2025-05-06T12:00:29","modified_gmt":"2025-05-06T04:00:29","slug":"%e4%b8%80%e5%af%b9%e5%a4%9a%e5%85%b3%e7%b3%bb%e4%b8%ad%e7%9a%84%e5%88%86%e9%a1%b5%e6%9f%a5%e8%af%a2%e5%92%8c%e8%bf%87%e6%bb%a4%ef%bc%9a%e5%a6%82%e4%bd%95%e9%ab%98%e6%95%88%e8%a7%a3%e5%86%b3join","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/200462\/","title":{"rendered":"\u4e00\u5bf9\u591a\u5173\u7cfb\u4e2d\u7684\u5206\u9875\u67e5\u8be2\u548c\u8fc7\u6ee4\uff1a\u5982\u4f55\u9ad8\u6548\u89e3\u51b3JOIN\u548c\u7b2c\u4e00\u8303\u5f0f\u51b2\u7a81\uff1f"},"content":{"rendered":"<p><b><\/b> <\/p>\n<h1>\u4e00\u5bf9\u591a\u5173\u7cfb\u4e2d\u7684\u5206\u9875\u67e5\u8be2\u548c\u8fc7\u6ee4\uff1a\u5982\u4f55\u9ad8\u6548\u89e3\u51b3JOIN\u548c\u7b2c\u4e00\u8303\u5f0f\u51b2\u7a81\uff1f<\/h1>\n<p>\u4eb2\u7231\u7684\u7f16\u7a0b\u5b66\u4e60\u7231\u597d\u8005\uff0c\u5982\u679c\u4f60\u70b9\u5f00\u4e86\u8fd9\u7bc7\u6587\u7ae0\uff0c\u8bf4\u660e\u4f60\u5bf9\u300a\u4e00\u5bf9\u591a\u5173\u7cfb\u4e2d\u7684\u5206\u9875\u67e5\u8be2\u548c\u8fc7\u6ee4\uff1a\u5982\u4f55\u9ad8\u6548\u89e3\u51b3JOIN\u548c\u7b2c\u4e00\u8303\u5f0f\u51b2\u7a81\uff1f\u300b\u5f88\u611f\u5174\u8da3\u3002\u672c\u7bc7\u6587\u7ae0\u5c31\u6765\u7ed9\u5927\u5bb6\u8be6\u7ec6\u89e3\u6790\u4e00\u4e0b\uff0c\u4e3b\u8981\u4ecb\u7ecd\u4e00\u4e0b\uff0c\u5e0c\u671b\u6240\u6709\u8ba4\u771f\u8bfb\u5b8c\u7684\u7ae5\u978b\u4eec\uff0c\u90fd\u6709\u5b9e\u8d28\u6027\u7684\u63d0\u9ad8\u3002<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.17golang.com\/uploads\/20241105\/1730807489672a06c1ec22f.jpg\" class=\"aligncenter\"><\/p>\n<p><strong>\u4e1a\u52a1\u5173\u7cfb\u4e3a\u4e00\u5bf9\u591a\u7684\u5206\u9875\u67e5\u8be2\u4e0e\u591a\u4fa7\u6761\u4ef6\u8fc7\u6ee4<\/strong><\/p>\n<p>\u5728\u4e1a\u52a1\u7cfb\u7edf\u4e2d\uff0c\u7ecf\u5e38\u4f1a\u9047\u5230\u4e00\u5bf9\u591a\u7684\u5173\u7cfb\uff0c\u5e76\u4e14\u9700\u8981\u5206\u9875\u67e5\u8be2\u548c\u6839\u636e\u591a\u4fa7\u6761\u4ef6\u8fdb\u884c\u8fc7\u6ee4\u7684\u9700\u6c42\u3002\u9488\u5bf9\u8fd9\u79cd\u60c5\u51b5\uff0c\u9700\u8981\u8bbe\u8ba1\u5408\u7406\u7684\u6570\u636e\u5e93\u8868\u7ed3\u6784\u548c\u67e5\u8be2\u65b9\u6848\u6765\u9ad8\u6548\u83b7\u53d6\u6570\u636e\u3002<\/p>\n<p>\u672c\u6587\u63d0\u51fa\u7684\u4e24\u79cd\u8bbe\u8ba1\u65b9\u6848\u5747\u5b58\u5728\u4e00\u5b9a\u7684\u95ee\u9898\uff1a<\/p>\n<ul>\n<li><strong>\u7b2c\u4e00\u79cd\u65b9\u6848\uff1a<\/strong>\u5c06\u6570\u636e\u5206\u6563\u5728\u4e24\u5f20\u8868\u4e2d\uff0c\u867d\u7136\u6ee1\u8db3\u4e86\u7b2c\u4e00\u8303\u5f0f\uff0c\u4f46\u5206\u9875\u67e5\u8be2\u65f6\u9700\u8981\u901a\u8fc7 join \u64cd\u4f5c\uff0c\u6570\u636e\u91cf\u8f83\u5927\u65f6\u6027\u80fd\u53ef\u80fd\u53d7\u5f71\u54cd\uff0c\u4e14\u67e5\u8be2\u6761\u4ef6\u8fc7\u6ee4\u4e0d\u51c6\u786e\u3002<\/li>\n<li><strong>\u7b2c\u4e8c\u79cd\u65b9\u6848\uff1a<\/strong>\u5c06\u6570\u636e\u5b58\u50a8\u5728\u5355\u8868\u4e2d\uff0c\u8fdd\u53cd\u4e86\u7b2c\u4e00\u8303\u5f0f\uff0c\u6570\u636e\u91cf\u5927\u65f6\u53ef\u80fd\u5b58\u5728\u6027\u80fd\u95ee\u9898\uff0c\u4e14 like \u67e5\u8be2\u7ed3\u679c\u4e0d\u591f\u51c6\u786e\u3002<\/li>\n<\/ul>\n<p>\u4e3a\u4e86\u89e3\u51b3\u8fd9\u4e9b\u95ee\u9898\uff0c\u53ef\u4ee5\u91c7\u7528\u4ee5\u4e0b\u4f18\u5316\u65b9\u6848\uff1a<\/p>\n<pre>select *, (select group_concat(tag) from tag where user_id = user.id and tag = '\u6d3b\u6cfc') as tags\nfrom user\nwhere exists(select 1 from tag where user_id = user.id and tag = '\u6d3b\u6cfc' limit 1)\nlimit #{current}, #{size};<\/pre>\n<p>\u8fd9\u4e2a\u65b9\u6848\u5229\u7528\u4e86 sql 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\u64cd\u4f5c\u3002<\/li>\n<li>group_concat\u5c06\u5339\u914d\u7684\u6807\u7b7e\u8fdb\u884c\u62fc\u63a5\uff0c\u65b9\u4fbf\u540e\u7eed\u5904\u7406\u3002<\/li>\n<\/ul>\n<p>\u56e0\u6b64\uff0c\u8be5\u67e5\u8be2\u53ef\u4ee5\u9ad8\u6548\u5730\u8fdb\u884c\u5206\u9875\u67e5\u8be2\u5e76\u6839\u636e\u591a\u4fa7\u6761\u4ef6\u8fc7\u6ee4\u6570\u636e\uff0c\u4fdd\u8bc1\u67e5\u8be2\u7ed3\u679c\u7684\u51c6\u786e\u6027\u3002<\/p>\n<p>\u4ee5\u4e0a\u5c31\u662f\u672c\u6587\u7684\u5168\u90e8\u5185\u5bb9\u4e86\uff0c\u662f\u5426\u6709\u987a\u5229\u5e2e\u52a9\u4f60\u89e3\u51b3\u95ee\u9898\uff1f\u82e5\u662f\u80fd\u7ed9\u4f60\u5e26\u6765\u5b66\u4e60\u4e0a\u7684\u5e2e\u52a9\uff0c\u8bf7\u5927\u5bb6\u591a\u591a\u652f\u6301\u4e3b\u673a\u5b9d\u8d1d\uff01\u66f4\u591a\u5173\u4e8e\u6570\u636e\u5e93\u7684\u76f8\u5173\u77e5\u8bc6\uff0c\u4e5f\u53ef\u5173\u6ce8\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\u3002<\/p>\n<dl>\n<dt>\n 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