{"id":60649,"date":"2024-10-13T04:38:14","date_gmt":"2024-10-12T20:38:14","guid":{"rendered":"https:\/\/server.hk\/cnblog\/60649\/"},"modified":"2024-10-13T04:38:14","modified_gmt":"2024-10-12T20:38:14","slug":"db2%e6%95%b8%e6%93%9a%e5%ba%abselect%e8%aa%9e%e5%8f%a5%e7%9a%843%e8%bc%83%e7%82%ba%e9%ab%98%e7%b4%9a%e7%9a%84%e7%94%a8%e6%b3%95","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/60649\/","title":{"rendered":"DB2\u6578\u64da\u5eabSELECT\u8a9e\u53e5\u76843\u8f03\u70ba\u9ad8\u7d1a\u7684\u7528\u6cd5"},"content":{"rendered":"

DB2\u6578\u64da\u5eabSELECT\u8a9e\u53e5\u76843\u8f03\u70ba\u9ad8\u7d1a\u7684\u7528\u6cd5<\/h1>\n

\u5728\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0cIBM\u7684DB2\u662f\u4e00\u500b\u529f\u80fd\u5f37\u5927\u7684\u9078\u64c7\uff0c\u7279\u5225\u662f\u5728\u8655\u7406\u5927\u578b\u6578\u64da\u96c6\u6642\u3002SELECT\u8a9e\u53e5\u662fDB2\u4e2d\u6700\u5e38\u7528\u7684\u67e5\u8a62\u8a9e\u53e5\u4e4b\u4e00\uff0c\u7136\u800c\uff0c\u9664\u4e86\u57fa\u672c\u7684\u67e5\u8a62\u529f\u80fd\u5916\uff0cDB2\u9084\u63d0\u4f9b\u4e86\u4e00\u4e9b\u9ad8\u7d1a\u7528\u6cd5\uff0c\u53ef\u4ee5\u5e6b\u52a9\u7528\u6236\u66f4\u6709\u6548\u5730\u5f9e\u6578\u64da\u5eab\u4e2d\u63d0\u53d6\u4fe1\u606f\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u4e09\u7a2e\u8f03\u70ba\u9ad8\u7d1a\u7684DB2 SELECT\u8a9e\u53e5\u7528\u6cd5\u3002<\/p>\n

1. \u4f7f\u7528\u5b50\u67e5\u8a62<\/h2>\n

\u5b50\u67e5\u8a62\u662f\u6307\u5728\u4e00\u500bSELECT\u8a9e\u53e5\u4e2d\u5d4c\u5957\u53e6\u4e00\u500bSELECT\u8a9e\u53e5\u3002\u9019\u7a2e\u65b9\u6cd5\u53ef\u4ee5\u7528\u4f86\u9032\u884c\u66f4\u8907\u96dc\u7684\u67e5\u8a62\uff0c\u7279\u5225\u662f\u5728\u9700\u8981\u6839\u64da\u5176\u4ed6\u67e5\u8a62\u7684\u7d50\u679c\u4f86\u904e\u6ffe\u6578\u64da\u6642\u3002<\/p>\n

SELECT emp_id, emp_name \nFROM employees \nWHERE dept_id IN (SELECT dept_id FROM departments WHERE location = 'Hong Kong');\n<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u5167\u90e8\u7684SELECT\u8a9e\u53e5\u9996\u5148\u67e5\u8a62\u4f4d\u65bc\u201c\u9999\u6e2f\u201d\u7684\u90e8\u9580ID\uff0c\u7136\u5f8c\u5916\u90e8\u7684SELECT\u8a9e\u53e5\u6839\u64da\u9019\u4e9b\u90e8\u9580ID\u4f86\u67e5\u8a62\u54e1\u5de5\u4fe1\u606f\u3002\u9019\u6a23\u7684\u67e5\u8a62\u65b9\u5f0f\u4f7f\u5f97\u6578\u64da\u7684\u904e\u6ffe\u66f4\u52a0\u9748\u6d3b\u3002<\/p>\n
2. \u4f7f\u7528\u7a97\u53e3\u51fd\u6578<\/h2>\n
\u7a97\u53e3\u51fd\u6578\u5141\u8a31\u7528\u6236\u5728\u67e5\u8a62\u7d50\u679c\u4e2d\u9032\u884c\u8a08\u7b97\uff0c\u800c\u4e0d\u9700\u8981\u5c07\u6578\u64da\u5206\u7d44\u3002\u9019\u5c0d\u65bc\u9700\u8981\u5728\u540c\u4e00\u67e5\u8a62\u4e2d\u986f\u793a\u539f\u59cb\u6578\u64da\u548c\u8a08\u7b97\u7d50\u679c\u7684\u60c5\u6cc1\u7279\u5225\u6709\u7528\u3002<\/p>\n
SELECT emp_id, emp_name, salary, \n       RANK() OVER (PARTITION BY dept_id ORDER BY salary DESC) AS salary_rank \nFROM employees;\n<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0cRANK()\u51fd\u6578\u6839\u64da\u6bcf\u500b\u90e8\u9580\u7684\u85aa\u6c34\u5c0d\u54e1\u5de5\u9032\u884c\u6392\u540d\u3002\u9019\u6a23\uff0c\u67e5\u8a62\u7d50\u679c\u4e2d\u4e0d\u50c5\u986f\u793a\u4e86\u54e1\u5de5\u7684\u57fa\u672c\u4fe1\u606f\uff0c\u9084\u986f\u793a\u4e86\u4ed6\u5011\u5728\u5404\u81ea\u90e8\u9580\u4e2d\u7684\u85aa\u6c34\u6392\u540d\uff0c\u9019\u5c0d\u65bc\u5206\u6790\u85aa\u6c34\u7d50\u69cb\u975e\u5e38\u6709\u5e6b\u52a9\u3002<\/p>\n
3. \u4f7f\u7528CTE\uff08\u516c\u7528\u8868\u8868\u9054\u5f0f\uff09<\/h2>\n
\u516c\u7528\u8868\u8868\u9054\u5f0f\uff08CTE\uff09\u662f\u4e00\u7a2e\u81e8\u6642\u7d50\u679c\u96c6\uff0c\u53ef\u4ee5\u5728SELECT\u8a9e\u53e5\u4e2d\u91cd\u8907\u4f7f\u7528\u3002\u9019\u5c0d\u65bc\u9700\u8981\u591a\u6b21\u5f15\u7528\u76f8\u540c\u67e5\u8a62\u7d50\u679c\u7684\u60c5\u6cc1\u7279\u5225\u6709\u7528\u3002<\/p>\n
WITH DeptSalaries AS (\n    SELECT dept_id, AVG(salary) AS avg_salary \n    FROM employees \n    GROUP BY dept_id\n)\nSELECT e.emp_id, e.emp_name, ds.avg_salary \nFROM employees e\nJOIN DeptSalaries ds ON e.dept_id = ds.dept_id\nWHERE e.salary > ds.avg_salary;\n<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0cCTE\u9996\u5148\u8a08\u7b97\u6bcf\u500b\u90e8\u9580\u7684\u5e73\u5747\u85aa\u6c34\uff0c\u7136\u5f8c\u5728\u4e3b\u67e5\u8a62\u4e2d\u4f7f\u7528\u9019\u500b\u7d50\u679c\u96c6\u4f86\u67e5\u8a62\u90a3\u4e9b\u85aa\u6c34\u9ad8\u65bc\u90e8\u9580\u5e73\u5747\u85aa\u6c34\u7684\u54e1\u5de5\u3002\u9019\u6a23\u7684\u67e5\u8a62\u65b9\u5f0f\u4f7f\u5f97\u4ee3\u78bc\u66f4\u52a0\u6e05\u6670\uff0c\u4e26\u4e14\u63d0\u9ad8\u4e86\u53ef\u8b80\u6027\u3002<\/p>\n
\u7e3d\u7d50<\/h2>\n
DB2\u7684SELECT\u8a9e\u53e5\u4e0d\u50c5\u50c5\u662f\u7528\u4f86\u67e5\u8a62\u6578\u64da\u7684\u5de5\u5177\uff0c\u9084\u63d0\u4f9b\u4e86\u591a\u7a2e\u9ad8\u7d1a\u7528\u6cd5\u4f86\u6eff\u8db3\u8907\u96dc\u7684\u67e5\u8a62\u9700\u6c42\u3002\u901a\u904e\u4f7f\u7528\u5b50\u67e5\u8a62\u3001\u7a97\u53e3\u51fd\u6578\u548c\u516c\u7528\u8868\u8868\u9054\u5f0f\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u66f4\u9748\u6d3b\u5730\u64cd\u4f5c\u6578\u64da\uff0c\u5f9e\u800c\u63d0\u9ad8\u6578\u64da\u5206\u6790\u7684\u6548\u7387\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u6578\u64da\u8655\u7406\u7684\u4f01\u696d\u4f86\u8aaa\uff0c\u9078\u64c7\u5408\u9069\u7684\u6578\u64da\u5eab\u89e3\u6c7a\u65b9\u6848\u81f3\u95dc\u91cd\u8981\u3002\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u53ef\u9760\u7684 \u9999\u6e2fVPS<\/a> \u670d\u52d9\u4f86\u652f\u6301\u60a8\u7684\u6578\u64da\u5eab\u9700\u6c42\uff0cServer.HK\u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\u4ee5\u6eff\u8db3\u60a8\u7684\u9700\u6c42\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u63a2\u7d22DB2\u6578\u64da\u5eab\u4e2dSELECT\u8a9e\u53e5\u7684\u4e09\u7a2e\u9ad8\u7d1a\u7528\u6cd5\uff0c\u63d0\u5347\u67e5\u8a62\u6548\u7387\u8207\u6578\u64da\u8655\u7406\u80fd\u529b\uff0c\u52a9\u4f60\u7cbe\u901a\u6578\u64da\u7ba1\u7406\u3002<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-60649","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/60649","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"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=60649"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/60649\/revisions"}],"predecessor-version":[{"id":60650,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/60649\/revisions\/60650"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=60649"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=60649"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=60649"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}