{"id":167993,"date":"2024-11-06T08:37:18","date_gmt":"2024-11-06T00:37:18","guid":{"rendered":"https:\/\/server.hk\/cnblog\/167993\/"},"modified":"2024-11-06T08:37:19","modified_gmt":"2024-11-06T00:37:19","slug":"%e8%81%8a%e8%81%8a-sql-%e4%b8%ad%e7%9a%84%e6%b5%81%e7%a8%8b%e6%8e%a7%e5%88%b6%ef%bc%8c%e4%bd%a0%e6%98%8e%e7%99%bd%e4%ba%86%e5%97%8e%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/167993\/","title":{"rendered":"\u804a\u804a SQL \u4e2d\u7684\u6d41\u7a0b\u63a7\u5236\uff0c\u4f60\u660e\u767d\u4e86\u55ce\uff1f"},"content":{"rendered":"

\u804a\u804a SQL \u4e2d\u7684\u6d41\u7a0b\u63a7\u5236\uff0c\u4f60\u660e\u767d\u4e86\u55ce\uff1f<\/h1>\n

\u5728\u8cc7\u6599\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0cSQL\uff08\u7d50\u69cb\u5316\u67e5\u8a62\u8a9e\u8a00\uff09\u4e0d\u50c5\u7528\u65bc\u67e5\u8a62\u548c\u64cd\u4f5c\u6578\u64da\uff0c\u9084\u63d0\u4f9b\u4e86\u6d41\u7a0b\u63a7\u5236\u7684\u529f\u80fd\uff0c\u4f7f\u5f97\u958b\u767c\u8005\u80fd\u5920\u7de8\u5beb\u66f4\u70ba\u8907\u96dc\u7684\u908f\u8f2f\u3002\u6d41\u7a0b\u63a7\u5236\u8a9e\u53e5\u5141\u8a31\u6211\u5011\u6839\u64da\u7279\u5b9a\u689d\u4ef6\u57f7\u884c\u4e0d\u540c\u7684\u64cd\u4f5c\uff0c\u9019\u5728\u8655\u7406\u696d\u52d9\u908f\u8f2f\u6642\u5c24\u70ba\u91cd\u8981\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e SQL \u4e2d\u7684\u6d41\u7a0b\u63a7\u5236\uff0c\u5e6b\u52a9\u4f60\u66f4\u597d\u5730\u7406\u89e3\u5176\u904b\u4f5c\u65b9\u5f0f\u3002<\/p>\n

\u6d41\u7a0b\u63a7\u5236\u7684\u57fa\u672c\u6982\u5ff5<\/h2>\n

\u6d41\u7a0b\u63a7\u5236\u8a9e\u53e5\u4e3b\u8981\u5305\u62ec\u689d\u4ef6\u8a9e\u53e5\u548c\u5faa\u74b0\u8a9e\u53e5\u3002\u9019\u4e9b\u8a9e\u53e5\u4f7f\u5f97 SQL \u80fd\u5920\u6839\u64da\u4e0d\u540c\u7684\u60c5\u6cc1\u57f7\u884c\u4e0d\u540c\u7684\u64cd\u4f5c\uff0c\u5f9e\u800c\u63d0\u9ad8\u4e86\u6578\u64da\u8655\u7406\u7684\u9748\u6d3b\u6027\u548c\u6548\u7387\u3002<\/p>\n

\u689d\u4ef6\u8a9e\u53e5<\/h3>\n

\u5728 SQL \u4e2d\uff0c\u6700\u5e38\u898b\u7684\u689d\u4ef6\u8a9e\u53e5\u662f IF...ELSE<\/code> \u8a9e\u53e5\u3002\u9019\u7a2e\u8a9e\u53e5\u5141\u8a31\u6839\u64da\u67d0\u500b\u689d\u4ef6\u7684\u771f\u5047\u4f86\u57f7\u884c\u4e0d\u540c\u7684 SQL \u8a9e\u53e5\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u7c21\u55ae\u7684\u7bc4\u4f8b\uff1a<\/p>\n

\nDECLARE @score INT;\nSET @score = 85;\n\nIF @score >= 60\nBEGIN\n    PRINT '\u901a\u904e';\nEND\nELSE\nBEGIN\n    PRINT '\u672a\u901a\u904e';\nEND\n<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u6839\u64da\u8b8a\u6578 @score<\/code> \u7684\u503c\uff0cSQL \u5c07\u8f38\u51fa\u201c\u901a\u904e\u201d\u6216\u201c\u672a\u901a\u904e\u201d\u3002\u9019\u7a2e\u689d\u4ef6\u5224\u65b7\u5728\u8a31\u591a\u696d\u52d9\u908f\u8f2f\u4e2d\u90fd\u975e\u5e38\u6709\u7528\u3002<\/p>\n
CASE \u8a9e\u53e5<\/h3>\n
\u9664\u4e86 IF...ELSE<\/code>\uff0cSQL \u9084\u63d0\u4f9b\u4e86 CASE<\/code> \u8a9e\u53e5\uff0c\u9019\u662f\u4e00\u7a2e\u66f4\u70ba\u9748\u6d3b\u7684\u689d\u4ef6\u5224\u65b7\u65b9\u5f0f\u3002CASE<\/code> \u8a9e\u53e5\u53ef\u4ee5\u5728\u4e00\u500b\u67e5\u8a62\u4e2d\u6839\u64da\u4e0d\u540c\u7684\u689d\u4ef6\u8fd4\u56de\u4e0d\u540c\u7684\u7d50\u679c\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528 CASE<\/code> \u7684\u7bc4\u4f8b\uff1a<\/p>\n
\nSELECT \n    Name,\n    CASE \n        WHEN Score >= 90 THEN '\u512a\u79c0'\n        WHEN Score >= 75 THEN '\u826f\u597d'\n        WHEN Score >= 60 THEN '\u53ca\u683c'\n        ELSE '\u4e0d\u53ca\u683c'\n    END AS Grade\nFROM Students;\n<\/code><\/pre>\n
\u9019\u6bb5 SQL \u8a9e\u53e5\u5c07\u6839\u64da\u5b78\u751f\u7684\u5206\u6578\u8fd4\u56de\u76f8\u61c9\u7684\u7b49\u7d1a\uff0c\u9019\u5728\u5831\u544a\u751f\u6210\u548c\u6578\u64da\u5206\u6790\u4e2d\u975e\u5e38\u6709\u7528\u3002<\/p>\n
\u5faa\u74b0\u8a9e\u53e5<\/h2>\n
\u9664\u4e86\u689d\u4ef6\u8a9e\u53e5\uff0cSQL \u9084\u652f\u6301\u5faa\u74b0\u8a9e\u53e5\uff0c\u5982 WHILE<\/code> \u5faa\u74b0\u3002\u9019\u7a2e\u8a9e\u53e5\u5141\u8a31\u6211\u5011\u91cd\u8907\u57f7\u884c\u67d0\u6bb5\u4ee3\u78bc\uff0c\u76f4\u5230\u6eff\u8db3\u7279\u5b9a\u689d\u4ef6\u70ba\u6b62\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528 WHILE<\/code> \u7684\u7bc4\u4f8b\uff1a<\/p>\n
\nDECLARE @counter INT;\nSET @counter = 1;\n\nWHILE @counter <= 5\nBEGIN\n    PRINT '\u8a08\u6578\u5668\u7684\u503c\u662f: ' + CAST(@counter AS VARCHAR);\n    SET @counter = @counter + 1;\nEND\n<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u8a08\u6578\u5668\u5f9e 1 \u958b\u59cb\uff0c\u6bcf\u6b21\u5faa\u74b0\u90fd\u6703\u8f38\u51fa\u7576\u524d\u7684\u8a08\u6578\u5668\u503c\uff0c\u76f4\u5230\u8a08\u6578\u5668\u9054\u5230 5\u3002<\/p>\n
\u7d50\u5408\u4f7f\u7528\u6d41\u7a0b\u63a7\u5236<\/h2>\n
\u5728\u5be6\u969b\u61c9\u7528\u4e2d\uff0c\u6d41\u7a0b\u63a7\u5236\u8a9e\u53e5\u7d93\u5e38\u9700\u8981\u7d50\u5408\u4f7f\u7528\uff0c\u4ee5\u5be6\u73fe\u66f4\u70ba\u8907\u96dc\u7684\u908f\u8f2f\u3002\u4f8b\u5982\uff0c\u6211\u5011\u53ef\u4ee5\u5728\u5faa\u74b0\u4e2d\u4f7f\u7528\u689d\u4ef6\u8a9e\u53e5\uff0c\u6839\u64da\u4e0d\u540c\u7684\u689d\u4ef6\u57f7\u884c\u4e0d\u540c\u7684\u64cd\u4f5c\u3002\u9019\u6a23\u7684\u7d44\u5408\u4f7f\u5f97 SQL \u7684\u529f\u80fd\u66f4\u52a0\u5f37\u5927\u3002<\/p>\n
\nDECLARE @i INT;\nSET @i = 1;\n\nWHILE @i <= 10\nBEGIN\n    IF @i % 2 = 0\n        PRINT @i + ' \u662f\u5076\u6578';\n    ELSE\n        PRINT @i + ' \u662f\u5947\u6578';\n    \n    SET @i = @i + 1;\nEND\n<\/code><\/pre>\n
\u9019\u6bb5\u4ee3\u78bc\u5c07\u8f38\u51fa\u5f9e 1 \u5230 10 \u7684\u6240\u6709\u6578\u5b57\uff0c\u4e26\u6a19\u660e\u5b83\u5011\u662f\u5947\u6578\u9084\u662f\u5076\u6578\u3002<\/p>\n
\u7e3d\u7d50<\/h2>\n
SQL \u4e2d\u7684\u6d41\u7a0b\u63a7\u5236\u8a9e\u53e5\u70ba\u958b\u767c\u8005\u63d0\u4f9b\u4e86\u5f37\u5927\u7684\u5de5\u5177\uff0c\u4f7f\u5f97\u6578\u64da\u8655\u7406\u548c\u696d\u52d9\u908f\u8f2f\u7684\u5be6\u73fe\u8b8a\u5f97\u66f4\u52a0\u9748\u6d3b\u548c\u9ad8\u6548\u3002\u901a\u904e\u4f7f\u7528\u689d\u4ef6\u8a9e\u53e5\u548c\u5faa\u74b0\u8a9e\u53e5\uff0c\u6211\u5011\u53ef\u4ee5\u6839\u64da\u4e0d\u540c\u7684\u60c5\u6cc1\u57f7\u884c\u76f8\u61c9\u7684\u64cd\u4f5c\uff0c\u5f9e\u800c\u63d0\u9ad8\u6578\u64da\u8655\u7406\u7684\u6548\u7387\u3002\u7121\u8ad6\u662f\u5728\u6578\u64da\u5206\u6790\u9084\u662f\u5831\u544a\u751f\u6210\u4e2d\uff0c\u638c\u63e1\u9019\u4e9b\u6d41\u7a0b\u63a7\u5236\u8a9e\u53e5\u90fd\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002<\/p>\n
\u5982\u679c\u4f60\u5c0d\u65bc \u9999\u6e2fVPS<\/a> \u670d\u52d9\u6709\u8208\u8da3\uff0c\u6216\u60f3\u4e86\u89e3\u66f4\u591a\u95dc\u65bc \u4f3a\u670d\u5668<\/a> \u7684\u8cc7\u8a0a\uff0c\u6b61\u8fce\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4ee5\u7372\u53d6\u66f4\u591a\u8a73\u7d30\u8cc7\u6599\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u63a2\u7d22 SQL \u4e2d\u7684\u6d41\u7a0b\u63a7\u5236\uff0c\u4e86\u89e3\u5982\u4f55\u4f7f\u7528\u6761\u4ef6\u8bed\u53e5\u548c\u5faa\u73af\u6765\u4f18\u5316\u6570\u636e\u5e93\u64cd\u4f5c\u548c\u63d0\u9ad8\u67e5\u8be2\u6548\u7387\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-167993","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/167993","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=167993"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/167993\/revisions"}],"predecessor-version":[{"id":167994,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/167993\/revisions\/167994"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=167993"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=167993"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=167993"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}