{"id":185234,"date":"2024-11-10T19:51:17","date_gmt":"2024-11-10T11:51:17","guid":{"rendered":"https:\/\/server.hk\/cnblog\/185234\/"},"modified":"2024-11-10T19:51:18","modified_gmt":"2024-11-10T11:51:18","slug":"%e4%bd%bf%e7%94%a8sql-server-case%e8%a1%a8%e9%81%94%e5%bc%8f%e4%bb%a3%e6%9b%bf%e5%8b%95%e6%85%8bsql","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/185234\/","title":{"rendered":"\u4f7f\u7528SQL Server CASE\u8868\u9054\u5f0f\u4ee3\u66ff\u52d5\u614bSQL"},"content":{"rendered":"

\u4f7f\u7528SQL Server CASE\u8868\u9054\u5f0f\u4ee3\u66ff\u52d5\u614bSQL<\/h1>\n

\u5728\u8cc7\u6599\u5eab\u7ba1\u7406\u4e2d\uff0cSQL Server\u662f\u4e00\u500b\u5ee3\u6cdb\u4f7f\u7528\u7684\u95dc\u806f\u5f0f\u8cc7\u6599\u5eab\u7ba1\u7406\u7cfb\u7d71\u3002\u7576\u958b\u767c\u8005\u9700\u8981\u6839\u64da\u4e0d\u540c\u7684\u689d\u4ef6\u4f86\u57f7\u884c\u67e5\u8a62\u6642\uff0c\u52d5\u614bSQL\u5e38\u5e38\u88ab\u7528\u4f86\u751f\u6210\u548c\u57f7\u884cSQL\u8a9e\u53e5\u3002\u7136\u800c\uff0c\u52d5\u614bSQL\u7684\u4f7f\u7528\u53ef\u80fd\u6703\u5c0e\u81f4\u5b89\u5168\u6027\u554f\u984c\uff0c\u4f8b\u5982SQL\u6ce8\u5165\u653b\u64ca\uff0c\u4e26\u4e14\u5728\u6027\u80fd\u4e0a\u4e5f\u53ef\u80fd\u4e0d\u5982\u9810\u671f\u3002\u9019\u6642\uff0c\u4f7f\u7528SQL Server\u7684CASE\u8868\u9054\u5f0f\u53ef\u4ee5\u662f\u4e00\u500b\u66f4\u5b89\u5168\u4e14\u9ad8\u6548\u7684\u66ff\u4ee3\u65b9\u6848\u3002<\/p>\n

\u4ec0\u9ebc\u662fCASE\u8868\u9054\u5f0f\uff1f<\/h2>\n

CASE\u8868\u9054\u5f0f\u662f\u4e00\u7a2e\u689d\u4ef6\u8a9e\u53e5\uff0c\u5141\u8a31\u958b\u767c\u8005\u5728SQL\u67e5\u8a62\u4e2d\u6839\u64da\u4e0d\u540c\u7684\u689d\u4ef6\u8fd4\u56de\u4e0d\u540c\u7684\u503c\u3002\u5b83\u53ef\u4ee5\u7528\u65bcSELECT\u3001UPDATE\u548cDELETE\u8a9e\u53e5\u4e2d\uff0c\u4e26\u4e14\u53ef\u4ee5\u5728\u67e5\u8a62\u4e2d\u9032\u884c\u591a\u91cd\u689d\u4ef6\u5224\u65b7\u3002<\/p>\n

CASE\u8868\u9054\u5f0f\u7684\u57fa\u672c\u8a9e\u6cd5<\/h3>\n
\nCASE \n    WHEN condition1 THEN result1\n    WHEN condition2 THEN result2\n    ...\n    ELSE resultN\nEND\n<\/code><\/pre>\n
\u5728\u9019\u6bb5\u8a9e\u6cd5\u4e2d\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u6839\u64da\u4e0d\u540c\u7684\u689d\u4ef6\u4f86\u8fd4\u56de\u76f8\u61c9\u7684\u7d50\u679c\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u7c21\u55ae\u7684\u4f8b\u5b50\uff1a<\/p>\n
\nSELECT \n    EmployeeName,\n    CASE \n        WHEN Salary > 50000 THEN '\u9ad8\u85aa'\n        WHEN Salary BETWEEN 30000 AND 50000 THEN '\u4e2d\u85aa'\n        ELSE '\u4f4e\u85aa'\n    END AS SalaryCategory\nFROM Employees;\n<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u6839\u64da\u54e1\u5de5\u7684\u85aa\u6c34\uff0cCASE\u8868\u9054\u5f0f\u5c07\u5176\u5206\u985e\u70ba\u9ad8\u85aa\u3001\u4e2d\u85aa\u6216\u4f4e\u85aa\uff0c\u9019\u6a23\u53ef\u4ee5\u907f\u514d\u4f7f\u7528\u52d5\u614bSQL\u4f86\u751f\u6210\u4e0d\u540c\u7684\u67e5\u8a62\u3002<\/p>\n
\u70ba\u4ec0\u9ebc\u9078\u64c7CASE\u8868\u9054\u5f0f\u800c\u975e\u52d5\u614bSQL\uff1f<\/h2>\n
1. \u5b89\u5168\u6027<\/h3>\n
\u52d5\u614bSQL\u5bb9\u6613\u53d7\u5230SQL\u6ce8\u5165\u653b\u64ca\u7684\u5a01\u8105\uff0c\u9019\u662f\u56e0\u70ba\u7528\u6236\u8f38\u5165\u7684\u6578\u64da\u53ef\u80fd\u6703\u88ab\u76f4\u63a5\u5d4c\u5165\u5230SQL\u8a9e\u53e5\u4e2d\u3002\u4f7f\u7528CASE\u8868\u9054\u5f0f\u53ef\u4ee5\u6e1b\u5c11\u9019\u7a2e\u98a8\u96aa\uff0c\u56e0\u70ba\u5b83\u4e0d\u9700\u8981\u62fc\u63a5SQL\u8a9e\u53e5\uff0c\u800c\u662f\u76f4\u63a5\u5728\u67e5\u8a62\u4e2d\u9032\u884c\u689d\u4ef6\u5224\u65b7\u3002<\/p>\n
2. \u6027\u80fd<\/h3>\n
\u52d5\u614bSQL\u5728\u57f7\u884c\u6642\u9700\u8981\u89e3\u6790\u548c\u7de8\u8b6f\uff0c\u9019\u53ef\u80fd\u6703\u5c0e\u81f4\u6027\u80fd\u4e0b\u964d\u3002\u76f8\u5c0d\u800c\u8a00\uff0cCASE\u8868\u9054\u5f0f\u5728\u67e5\u8a62\u57f7\u884c\u6642\u5df2\u7d93\u88ab\u89e3\u6790\uff0c\u9019\u6a23\u53ef\u4ee5\u63d0\u9ad8\u67e5\u8a62\u7684\u57f7\u884c\u6548\u7387\u3002<\/p>\n
3. \u53ef\u8b80\u6027\u548c\u7dad\u8b77\u6027<\/h3>\n
\u4f7f\u7528CASE\u8868\u9054\u5f0f\u53ef\u4ee5\u4f7fSQL\u67e5\u8a62\u66f4\u52a0\u7c21\u6f54\u548c\u6613\u65bc\u7406\u89e3\u3002\u7576\u67e5\u8a62\u4e2d\u5305\u542b\u591a\u500b\u689d\u4ef6\u6642\uff0cCASE\u8868\u9054\u5f0f\u80fd\u5920\u6e05\u6670\u5730\u986f\u793a\u51fa\u6bcf\u500b\u689d\u4ef6\u7684\u908f\u8f2f\uff0c\u9019\u5c0d\u65bc\u5f8c\u7e8c\u7684\u7dad\u8b77\u548c\u4fee\u6539\u90fd\u975e\u5e38\u6709\u5e6b\u52a9\u3002<\/p>\n
\u5be6\u969b\u61c9\u7528\u6848\u4f8b<\/h2>\n
\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u92b7\u552e\u6578\u64da\u8868\uff0c\u4e26\u5e0c\u671b\u6839\u64da\u92b7\u552e\u984d\u4f86\u8a55\u4f30\u92b7\u552e\u4eba\u54e1\u7684\u8868\u73fe\u3002\u6211\u5011\u53ef\u4ee5\u4f7f\u7528CASE\u8868\u9054\u5f0f\u4f86\u751f\u6210\u4e00\u500b\u5831\u544a\uff0c\u986f\u793a\u6bcf\u4f4d\u92b7\u552e\u4eba\u54e1\u7684\u8868\u73fe\u7b49\u7d1a\uff1a<\/p>\n
\nSELECT \n    SalesPerson,\n    SalesAmount,\n    CASE \n        WHEN SalesAmount >= 100000 THEN '\u512a\u79c0'\n        WHEN SalesAmount BETWEEN 50000 AND 99999 THEN '\u826f\u597d'\n        ELSE '\u5f85\u6539\u9032'\n    END AS Performance\nFROM SalesData;\n<\/code><\/pre>\n
\u9019\u6a23\u7684\u67e5\u8a62\u4e0d\u50c5\u7c21\u5316\u4e86\u908f\u8f2f\uff0c\u9084\u63d0\u9ad8\u4e86\u67e5\u8a62\u7684\u5b89\u5168\u6027\u548c\u6027\u80fd\u3002<\/p>\n
\u7d50\u8ad6<\/h2>\n
\u7e3d\u7d50\u4f86\u8aaa\uff0c\u4f7f\u7528SQL Server\u7684CASE\u8868\u9054\u5f0f\u4f86\u4ee3\u66ff\u52d5\u614bSQL\u662f\u4e00\u500b\u660e\u667a\u7684\u9078\u64c7\u3002\u5b83\u4e0d\u50c5\u80fd\u63d0\u9ad8\u67e5\u8a62\u7684\u5b89\u5168\u6027\u548c\u6027\u80fd\uff0c\u9084\u80fd\u589e\u5f37\u4ee3\u78bc\u7684\u53ef\u8b80\u6027\u548c\u7dad\u8b77\u6027\u3002\u5728\u9032\u884c\u8cc7\u6599\u5eab\u958b\u767c\u6642\uff0c\u958b\u767c\u8005\u61c9\u8a72\u8003\u616e\u4f7f\u7528CASE\u8868\u9054\u5f0f\u4f86\u8655\u7406\u689d\u4ef6\u908f\u8f2f\uff0c\u4ee5\u4fbf\u66f4\u6709\u6548\u5730\u7ba1\u7406\u8cc7\u6599\u5eab\u64cd\u4f5c\u3002<\/p>\n
\u5982\u9700\u4e86\u89e3\u66f4\u591a\u6709\u95dc\u9999\u6e2fVPS<\/a>\u548c\u4f3a\u670d\u5668<\/a>\u7684\u8cc7\u8a0a\uff0c\u8acb\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u63a2\u7d22\u5982\u4f55\u4f7f\u7528SQL Server\u7684CASE\u8868\u9054\u5f0f\u66ff\u4ee3\u52d5\u614bSQL\uff0c\u63d0\u5347\u67e5\u8a62\u6548\u7387\u8207\u53ef\u8b80\u6027\uff0c\u7c21\u5316\u6578\u64da\u8655\u7406\u904e\u7a0b\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-185234","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/185234","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=185234"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/185234\/revisions"}],"predecessor-version":[{"id":185235,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/185234\/revisions\/185235"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=185234"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=185234"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=185234"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}