{"id":200239,"date":"2025-05-06T09:50:44","date_gmt":"2025-05-06T01:50:44","guid":{"rendered":"https:\/\/server.hk\/cnblog\/200239\/"},"modified":"2025-05-06T09:50:44","modified_gmt":"2025-05-06T01:50:44","slug":"%e5%a6%82%e4%bd%95%e8%ae%a9-mysql-%e4%b8%ad%e7%9a%84%e8%ae%a2%e5%8d%95%e6%8c%89%e7%85%a7%e7%8a%b6%e6%80%81%e6%8e%92%e5%ba%8f%ef%bc%8c%e4%bd%bf-2-%e5%a7%8b%e7%bb%88%e6%8e%92%e6%9c%80","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/200239\/","title":{"rendered":"\u5982\u4f55\u8ba9 MySQL \u4e2d\u7684\u8ba2\u5355\u6309\u7167\u72b6\u6001\u6392\u5e8f\uff0c\u4f7f \u201c2\u201d \u59cb\u7ec8\u6392\u6700\u524d\uff0c\u201c-1\u201d \u6392\u6700\u540e\uff1f"},"content":{"rendered":"<p><b><\/b> <\/p>\n<h1>\u5982\u4f55\u8ba9 MySQL \u4e2d\u7684\u8ba2\u5355\u6309\u7167\u72b6\u6001\u6392\u5e8f\uff0c\u4f7f \u201c2\u201d \u59cb\u7ec8\u6392\u6700\u524d\uff0c\u201c-1\u201d \u6392\u6700\u540e\uff1f<\/h1>\n<p>\u201c\u7eb5\u6709\u75be\u98ce\u6765\uff0c\u4eba\u751f\u4e0d\u8a00\u5f03\u201d\uff0c\u8fd9\u53e5\u8bdd\u9001\u7ed9\u6b63\u5728\u5b66\u4e60\u7684\u670b\u53cb\u4eec\uff0c\u4e5f\u5e0c\u671b\u5728\u9605\u8bfb\u672c\u6587\u540e\uff0c\u80fd\u591f\u771f\u7684\u5e2e\u52a9\u5230\u5927\u5bb6\u3002\u6211\u4e5f\u4f1a\u5728\u540e\u7eed\u7684\u6587\u7ae0\u4e2d\uff0c\u9646\u7eed\u66f4\u65b0\u76f8\u5173\u7684\u6280\u672f\u6587\u7ae0\uff0c\u6709\u597d\u7684\u5efa\u8bae\u6b22\u8fce\u5927\u5bb6\u5728\u8bc4\u8bba\u7559\u8a00\uff0c\u975e\u5e38\u611f\u8c22\uff01<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.17golang.com\/uploads\/20241030\/1730246807672178979ae2f.jpg\" class=\"aligncenter\"><\/p>\n<p><strong>\u5982\u4f55\u6309\u7167\u8ba2\u5355\u72b6\u6001\u6392\u5e8f mysql \u6570\u636e\uff0c\u8ba9\u201c-1\u201d\u59cb\u7ec8\u6392\u6700\u540e\uff0c\u201c2\u201d\u6392\u6700\u524d<\/strong><\/p>\n<p>\u5728 mysql \u4e2d\uff0c\u6392\u5e8f\u67e5\u8be2\u65f6\u6309\u72b6\u6001\u5bf9\u8ba2\u5355\u8868\u8fdb\u884c\u6392\u5e8f\u65f6\uff0c\u53ef\u4ee5\u6839\u636e\u4e0d\u540c\u7684\u72b6\u6001\u5206\u914d\u7279\u5b9a\u7684\u6392\u5e8f\u503c\uff0c\u4ece\u800c\u5b9e\u73b0\u81ea\u5b9a\u4e49\u6392\u5e8f\u89c4\u5219\u3002<\/p>\n<p><strong>sql \u4ee3\u7801\uff1a<\/strong><\/p>\n<pre>select * from (\n    select\n        case\n            when status == 2 then 7\n            when status == -1 then -1\n            else status\n        end as newStatus,\n        status\n    from m_table\n) m order by newStatus desc;<\/pre>\n<p><strong>\u89e3\u91ca\uff1a<\/strong><\/p>\n<ul>\n<li>\n<p>case \u8bed\u53e5\u6839\u636e\u4e0d\u540c\u7684\u72b6\u6001\u503c\u5206\u914d\u65b0\u7684\u6392\u5e8f\u503c newstatus\uff1a<\/p>\n<ul>\n<li>\u5982\u679c status \u4e3a 2\uff08\u5f85\u64cd\u4f5c\uff09\uff0c\u5219 newstatus \u4e3a 7\u3002<\/li>\n<li>\u5982\u679c status \u4e3a -1\uff08\u64a4\u9500\uff09\uff0c\u5219 newstatus \u4e3a -1\u3002<\/li>\n<li>\u5176\u4ed6\u72b6\u6001\u4fdd\u6301\u539f\u6765\u7684\u503c\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\u7136\u540e\uff0c\u6839\u636e newstatus \u5217\u5bf9\u7ed3\u679c\u8fdb\u884c\u964d\u5e8f\u6392\u5e8f\u3002<\/li>\n<\/ul>\n<p>\u8fd9\u6837\uff0c\u5f85\u64cd\u4f5c\u72b6\u6001\uff08status \u4e3a 2\uff09\u59cb\u7ec8\u6392\u5728\u6700\u524d\u9762\uff08newstatus \u4e3a 7\uff09\uff0c\u64a4\u9500\u72b6\u6001\uff08status \u4e3a -1\uff09\u59cb\u7ec8\u6392\u5728\u6700\u540e\uff08newstatus \u4e3a -1\uff09\uff0c\u5176\u4ed6\u72b6\u6001\u6309\u5347\u5e8f\u6392\u5217\u3002<\/p>\n<p>\u7406\u8bba\u8981\u638c\u63e1\uff0c\u5b9e\u64cd\u4e0d\u80fd\u843d\uff01\u4ee5\u4e0a\u5173\u4e8e\u300a\u5982\u4f55\u8ba9 MySQL \u4e2d\u7684\u8ba2\u5355\u6309\u7167\u72b6\u6001\u6392\u5e8f\uff0c\u4f7f \u201c2\u201d \u59cb\u7ec8\u6392\u6700\u524d\uff0c\u201c-1\u201d 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