{"id":200364,"date":"2025-05-06T08:29:03","date_gmt":"2025-05-06T00:29:03","guid":{"rendered":"https:\/\/server.hk\/cnblog\/200364\/"},"modified":"2025-05-06T08:29:03","modified_gmt":"2025-05-06T00:29:03","slug":"%e5%a6%82%e4%bd%95%e4%bd%bf%e7%94%a8-mysql-%e6%9f%a5%e8%af%a2%e7%bb%84%e5%90%88%e4%b8%8d%e5%90%8c%e5%ad%97%e6%ae%b5%e7%94%9f%e6%88%90%e6%96%b0%e5%ad%97%e6%ae%b5%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/200364\/","title":{"rendered":"\u5982\u4f55\u4f7f\u7528 MySQL \u67e5\u8be2\u7ec4\u5408\u4e0d\u540c\u5b57\u6bb5\u751f\u6210\u65b0\u5b57\u6bb5\uff1f"},"content":{"rendered":"<p><b><\/b> <\/p>\n<h1>\u5982\u4f55\u4f7f\u7528 MySQL \u67e5\u8be2\u7ec4\u5408\u4e0d\u540c\u5b57\u6bb5\u751f\u6210\u65b0\u5b57\u6bb5\uff1f<\/h1>\n<p>\u6570\u636e\u5e93\u5c0f\u767d\u4e00\u679a\uff0c\u6b63\u5728\u4e0d\u65ad\u5b66\u4e60\u79ef\u7d2f\u77e5\u8bc6\uff0c\u73b0\u5c06\u5b66\u4e60\u5230\u7684\u77e5\u8bc6\u8bb0\u5f55\u4e00\u4e0b\uff0c\u4e5f\u662f\u5c06\u6211\u7684\u6240\u5f97\u5206\u4eab\u7ed9\u5927\u5bb6\uff01\u800c\u4eca\u5929\u8fd9\u7bc7\u6587\u7ae0\u300a\u5982\u4f55\u4f7f\u7528 MySQL \u67e5\u8be2\u7ec4\u5408\u4e0d\u540c\u5b57\u6bb5\u751f\u6210\u65b0\u5b57\u6bb5\uff1f\u300b\u5e26\u5927\u5bb6\u6765\u4e86\u89e3\u4e00\u4e0b##content_title##\uff0c\u5e0c\u671b\u5bf9\u5927\u5bb6\u7684\u77e5\u8bc6\u79ef\u7d2f\u6709\u6240\u5e2e\u52a9\uff0c\u4ece\u800c\u5f25\u8865\u81ea\u5df1\u7684\u4e0d\u8db3\uff0c\u52a9\u529b\u5b9e\u6218\u5f00\u53d1\uff01<\/p>\n<p><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.17golang.com\/uploads\/20241103\/17305970896726d0e1cda34.jpg\" class=\"aligncenter\"><\/p>\n<p><strong>\u5982\u4f55\u4f7f\u7528 mysql \u67e5\u8be2\u89c4\u5219\u7ec4\u5408\u4e0d\u540c\u5b57\u6bb5\u751f\u6210\u65b0\u5b57\u6bb5\uff1f<\/strong><\/p>\n<p>\u5047\u8bbe\u6211\u4eec\u6709\u4e00\u4e2a\u8868\u683c\uff0c\u5176\u4e2d\u4fdd\u5b58\u4e86\u4e24\u5217\u4ef7\u683c\u4fe1\u606f\uff1a\u201c\u4ef7\u683c1\u201d\u548c\u201c\u4ef7\u683c2\u201d\u3002\u6211\u4eec\u9700\u8981\u521b\u5efa\u4e00\u4e2a\u65b0\u5b57\u6bb5\u201c\u4ef7\u683c\u201d\uff0c\u5176\u89c4\u5219\u5982\u4e0b\uff1a<\/p>\n<ul>\n<li>\u5982\u679c\u201c\u4ef7\u683c2\u201d\u4e0d\u4e3a\u7a7a\uff0c\u5219\u201c\u4ef7\u683c\u201d\u4e3a\u201c\u4ef7\u683c2\u201d\u3002<\/li>\n<li>\u5982\u679c\u201c\u4ef7\u683c2\u201d\u4e3a\u7a7a\uff0c\u5219\u201c\u4ef7\u683c\u201d\u4e3a\u201c\u4ef7\u683c1\u201d\u3002<\/li>\n<\/ul>\n<p>\u8981\u83b7\u5f97\u7b26\u5408\u8fd9\u4e9b\u89c4\u5219\u7684\u4ef7\u683c\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b mysql \u67e5\u8be2\uff1a<\/p>\n<pre>select id, if (\u4ef7\u683c2 is not null, \u4ef7\u683c2\uff0c\u4ef7\u683c1) as price<\/pre>\n<p>\u5728\u8fd9\u4e2a\u67e5\u8be2\u4e2d\uff0c\u6211\u4eec\u4f7f\u7528 if() \u51fd\u6570\u6765\u68c0\u67e5 \u4ef7\u683c2 \u662f\u5426\u4e3a\u7a7a\u3002\u5982\u679c\u4e3a\u7a7a\uff0cif() \u51fd\u6570\u5c06\u8fd4\u56de \u4ef7\u683c1\uff1b\u5426\u5219\uff0c\u5c06\u8fd4\u56de \u4ef7\u683c2\u3002<\/p>\n<p>\u67e5\u8be2\u7ed3\u679c\u5c06\u4e3a\u6211\u4eec\u63d0\u4f9b\u4e00\u4e2a\u5e26\u6709\u65b0\u5b57\u6bb5\u201c\u4ef7\u683c\u201d\u7684\u65b0\u7ed3\u679c\u96c6\uff0c\u8be5\u5b57\u6bb5\u5305\u542b\u6839\u636e\u4ee5\u4e0a\u89c4\u5219\u8ba1\u7b97\u7684\u4ef7\u683c\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 <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"<p>\u5982\u4f55\u4f7f\u7528 MySQL 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