{"id":168545,"date":"2024-11-06T13:16:17","date_gmt":"2024-11-06T05:16:17","guid":{"rendered":"https:\/\/server.hk\/cnblog\/168545\/"},"modified":"2024-11-06T13:16:18","modified_gmt":"2024-11-06T05:16:18","slug":"sql-%e4%b8%ad%e5%90%8c%e5%88%97%e7%9b%b8%e5%8a%a0%e7%9a%84%e6%96%b9%e6%b3%95","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/168545\/","title":{"rendered":"SQL \u4e2d\u540c\u5217\u76f8\u52a0\u7684\u65b9\u6cd5"},"content":{"rendered":"

SQL \u4e2d\u540c\u5217\u76f8\u52a0\u7684\u65b9\u6cd5<\/h1>\n

\u5728\u8cc7\u6599\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0cSQL\uff08\u7d50\u69cb\u5316\u67e5\u8a62\u8a9e\u8a00\uff09\u662f\u4e00\u7a2e\u7528\u65bc\u67e5\u8a62\u548c\u64cd\u4f5c\u8cc7\u6599\u7684\u6a19\u6e96\u8a9e\u8a00\u3002\u7576\u6211\u5011\u9700\u8981\u5c0d\u540c\u4e00\u5217\u7684\u6578\u64da\u9032\u884c\u76f8\u52a0\u6642\uff0cSQL \u63d0\u4f9b\u4e86\u591a\u7a2e\u65b9\u6cd5\u4f86\u5be6\u73fe\u9019\u4e00\u9700\u6c42\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u5e7e\u7a2e\u5e38\u898b\u7684 SQL \u4e2d\u540c\u5217\u76f8\u52a0\u7684\u65b9\u6cd5\uff0c\u4e26\u63d0\u4f9b\u76f8\u61c9\u7684\u7bc4\u4f8b\u4ee3\u78bc\u3002<\/p>\n

\u4f7f\u7528 SUM \u51fd\u6578<\/h2>\n

\u6700\u5e38\u898b\u7684\u65b9\u5f0f\u662f\u4f7f\u7528 SQL \u7684\u805a\u5408\u51fd\u6578 SUM()<\/code>\u3002\u9019\u500b\u51fd\u6578\u53ef\u4ee5\u5c0d\u6307\u5b9a\u5217\u7684\u6240\u6709\u6578\u503c\u9032\u884c\u52a0\u7e3d\uff0c\u4e26\u8fd4\u56de\u7e3d\u548c\u3002<\/p>\n

SELECT SUM(column_name) AS total\nFROM table_name;\n<\/code><\/pre>\n
\u5728\u9019\u500b\u7bc4\u4f8b\u4e2d\uff0ccolumn_name<\/code> \u662f\u4f60\u60f3\u8981\u76f8\u52a0\u7684\u5217\u540d\uff0c\u800c table_name<\/code> \u5247\u662f\u5305\u542b\u8a72\u5217\u7684\u8cc7\u6599\u8868\u540d\u3002AS total<\/code> \u662f\u7528\u4f86\u7d66\u7d50\u679c\u547d\u540d\u7684\u5225\u540d\u3002<\/p>\n
\u7bc4\u4f8b<\/h3>\n
SELECT SUM(salary) AS total_salary\nFROM employees;\n<\/code><\/pre>\n
\u9019\u500b\u67e5\u8a62\u5c07\u8fd4\u56de employees<\/code> \u8868\u4e2d\u6240\u6709\u54e1\u5de5\u85aa\u6c34\u7684\u7e3d\u548c\u3002<\/p>\n
\u4f7f\u7528 GROUP BY \u5b50\u53e5<\/h2>\n
\u5982\u679c\u4f60\u9700\u8981\u6839\u64da\u67d0\u500b\u7279\u5b9a\u7684\u5217\u9032\u884c\u5206\u7d44\u4e26\u8a08\u7b97\u6bcf\u7d44\u7684\u7e3d\u548c\uff0c\u53ef\u4ee5\u4f7f\u7528 GROUP BY<\/code> \u5b50\u53e5\u3002\u9019\u6a23\u53ef\u4ee5\u5c0d\u6bcf\u500b\u5206\u7d44\u7684\u6578\u64da\u9032\u884c\u76f8\u52a0\u3002<\/p>\n
SELECT department, SUM(salary) AS total_salary\nFROM employees\nGROUP BY department;\n<\/code><\/pre>\n
\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u7d50\u679c\u5c07\u986f\u793a\u6bcf\u500b\u90e8\u9580\u7684\u7e3d\u85aa\u6c34\u3002<\/p>\n
\u7bc4\u4f8b<\/h3>\n
SELECT department, SUM(salary) AS total_salary\nFROM employees\nGROUP BY department;\n<\/code><\/pre>\n
\u9019\u5c07\u8fd4\u56de\u6bcf\u500b\u90e8\u9580\u7684\u85aa\u6c34\u7e3d\u548c\uff0c\u5e6b\u52a9\u7ba1\u7406\u5c64\u4e86\u89e3\u5404\u90e8\u9580\u7684\u85aa\u8cc7\u652f\u51fa\u60c5\u6cc1\u3002<\/p>\n
\u4f7f\u7528 CASE \u8a9e\u53e5\u9032\u884c\u689d\u4ef6\u76f8\u52a0<\/h2>\n
\u6709\u6642\u5019\uff0c\u6211\u5011\u53ef\u80fd\u9700\u8981\u6839\u64da\u7279\u5b9a\u689d\u4ef6\u4f86\u9032\u884c\u76f8\u52a0\u3002\u9019\u6642\u53ef\u4ee5\u4f7f\u7528 CASE<\/code> \u8a9e\u53e5\u4f86\u5be6\u73fe\u689d\u4ef6\u52a0\u7e3d\u3002<\/p>\n
SELECT SUM(CASE WHEN status = 'active' THEN salary ELSE 0 END) AS active_salary\nFROM employees;\n<\/code><\/pre>\n
\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u53ea\u6709\u7576\u54e1\u5de5\u7684\u72c0\u614b\u70ba ‘active’ \u6642\uff0c\u624d\u6703\u5c07\u5176\u85aa\u6c34\u8a08\u5165\u7e3d\u548c\u3002<\/p>\n
\u7bc4\u4f8b<\/h3>\n
SELECT SUM(CASE WHEN status = 'active' THEN salary ELSE 0 END) AS active_salary\nFROM employees;\n<\/code><\/pre>\n
\u9019\u5c07\u8fd4\u56de\u6240\u6709\u5728\u8077\u54e1\u5de5\u7684\u85aa\u6c34\u7e3d\u548c\uff0c\u5c0d\u65bc\u4eba\u529b\u8cc7\u6e90\u90e8\u9580\u4f86\u8aaa\uff0c\u9019\u662f\u4e00\u500b\u975e\u5e38\u6709\u7528\u7684\u6307\u6a19\u3002<\/p>\n
\u7d50\u8ad6<\/h2>\n
\u5728 SQL \u4e2d\uff0c\u5c0d\u540c\u4e00\u5217\u9032\u884c\u76f8\u52a0\u7684\u65b9\u5f0f\u6709\u5f88\u591a\u7a2e\uff0c\u6839\u64da\u4e0d\u540c\u7684\u9700\u6c42\u53ef\u4ee5\u9078\u64c7\u5408\u9069\u7684\u65b9\u6cd5\u3002\u7121\u8ad6\u662f\u4f7f\u7528 SUM()<\/code> \u51fd\u6578\u3001GROUP BY<\/code> \u5b50\u53e5\uff0c\u9084\u662f CASE<\/code> \u8a9e\u53e5\uff0c\u9019\u4e9b\u5de5\u5177\u90fd\u80fd\u5e6b\u52a9\u6211\u5011\u6709\u6548\u5730\u8655\u7406\u6578\u64da\u3002<\/p>\n
\u5982\u679c\u4f60\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 \u9999\u6e2fVPS<\/a> \u89e3\u6c7a\u65b9\u6848\u4f86\u904b\u884c\u4f60\u7684\u8cc7\u6599\u5eab\uff0cServer.HK \u63d0\u4f9b\u4e86\u591a\u7a2e\u9078\u64c7\uff0c\u6eff\u8db3\u4e0d\u540c\u7528\u6236\u7684\u9700\u6c42\u3002\u7121\u8ad6\u662f\u5c0f\u578b\u4f01\u696d\u9084\u662f\u5927\u578b\u4f01\u696d\uff0c\u6211\u5011\u7684 \u4f3a\u670d\u5668<\/a> \u90fd\u80fd\u63d0\u4f9b\u7a69\u5b9a\u7684\u6027\u80fd\u548c\u5b89\u5168\u6027\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u4e86\u89e3 SQL \u4e2d\u540c\u5217\u76f8\u52a0\u7684\u65b9\u6cd5\uff0c\u638c\u63e1\u4f7f\u7528 SUM \u51fd\u6570\u548c GROUP BY \u8bed\u53e5\u8fdb\u884c\u6570\u636e\u6c47\u603b\u7684\u6280\u5de7\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-168545","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168545","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=168545"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168545\/revisions"}],"predecessor-version":[{"id":168546,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168545\/revisions\/168546"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=168545"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=168545"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=168545"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}