{"id":60651,"date":"2024-10-13T04:39:12","date_gmt":"2024-10-12T20:39:12","guid":{"rendered":"https:\/\/server.hk\/cnblog\/60651\/"},"modified":"2024-10-13T04:39:12","modified_gmt":"2024-10-12T20:39:12","slug":"db2%e6%95%b8%e6%93%9a%e5%ba%abselect%e8%aa%9e%e5%8f%a5%e7%9a%84%e4%b8%89%e7%a8%ae%e9%ab%98%e7%b4%9a%e7%94%a8%e6%b3%95","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/60651\/","title":{"rendered":"DB2\u6578\u64da\u5eabSELECT\u8a9e\u53e5\u7684\u4e09\u7a2e\u9ad8\u7d1a\u7528\u6cd5"},"content":{"rendered":"

DB2\u6578\u64da\u5eabSELECT\u8a9e\u53e5\u7684\u4e09\u7a2e\u9ad8\u7d1a\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\u80fd\u5920\u5f9e\u6578\u64da\u8868\u4e2d\u6aa2\u7d22\u6578\u64da\u3002\u672c\u6587\u5c07\u63a2\u8a0eDB2\u6578\u64da\u5eabSELECT\u8a9e\u53e5\u7684\u4e09\u7a2e\u9ad8\u7d1a\u7528\u6cd5\uff0c\u5e6b\u52a9\u958b\u767c\u8005\u66f4\u6709\u6548\u5730\u5229\u7528\u9019\u4e00\u5de5\u5177\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 employee_id, employee_name \nFROM employees \nWHERE department_id IN (SELECT department_id \n                        FROM departments \n                        WHERE location_id = 1000);\n<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u5167\u90e8\u7684SELECT\u8a9e\u53e5\u9996\u5148\u67e5\u8a62\u4f4d\u65bc\u7279\u5b9a\u5730\u9ede\u7684\u90e8\u9580ID\uff0c\u7136\u5f8c\u5916\u90e8\u7684SELECT\u8a9e\u53e5\u6839\u64da\u9019\u4e9b\u90e8\u9580ID\u6aa2\u7d22\u54e1\u5de5\u4fe1\u606f\u3002\u9019\u6a23\u7684\u67e5\u8a62\u65b9\u5f0f\u80fd\u5920\u6709\u6548\u5730\u7e2e\u5c0f\u67e5\u8a62\u7bc4\u570d\uff0c\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u3002<\/p>\n
2. \u4f7f\u7528\u806f\u63a5\uff08JOIN\uff09<\/h2>\n
\u806f\u63a5\u662f\u5c07\u591a\u500b\u8868\u4e2d\u7684\u6578\u64da\u6839\u64da\u67d0\u4e9b\u689d\u4ef6\u9032\u884c\u7d44\u5408\u7684\u904e\u7a0b\u3002DB2\u652f\u6301\u591a\u7a2e\u806f\u63a5\u985e\u578b\uff0c\u5305\u62ec\u5167\u90e8\u806f\u63a5\uff08INNER JOIN\uff09\u3001\u5916\u90e8\u806f\u63a5\uff08OUTER JOIN\uff09\u7b49\u3002\u4f7f\u7528\u806f\u63a5\u53ef\u4ee5\u5728\u4e00\u500b\u67e5\u8a62\u4e2d\u7372\u53d6\u4f86\u81ea\u591a\u500b\u8868\u7684\u6578\u64da\u3002<\/p>\n
SELECT e.employee_id, e.employee_name, d.department_name \nFROM employees e \nJOIN departments d ON e.department_id = d.department_id;\n<\/code><\/pre>\n
\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u6211\u5011\u4f7f\u7528INNER JOIN\u5c07\u54e1\u5de5\u8868\u548c\u90e8\u9580\u8868\u806f\u63a5\u5728\u4e00\u8d77\uff0c\u6839\u64da\u90e8\u9580ID\u4f86\u6aa2\u7d22\u54e1\u5de5\u53ca\u5176\u6240\u5c6c\u90e8\u9580\u7684\u540d\u7a31\u3002\u9019\u7a2e\u65b9\u6cd5\u4e0d\u50c5\u7c21\u5316\u4e86\u67e5\u8a62\uff0c\u9084\u80fd\u5920\u63d0\u4f9b\u66f4\u5168\u9762\u7684\u6578\u64da\u8996\u5716\u3002<\/p>\n
3. \u4f7f\u7528\u7a97\u53e3\u51fd\u6578\uff08Window Functions\uff09<\/h2>\n
\u7a97\u53e3\u51fd\u6578\u662f\u4e00\u7a2e\u5f37\u5927\u7684\u5de5\u5177\uff0c\u53ef\u4ee5\u5728\u67e5\u8a62\u4e2d\u9032\u884c\u8a08\u7b97\uff0c\u800c\u4e0d\u9700\u8981\u5c07\u6578\u64da\u5206\u7d44\u3002\u9019\u4f7f\u5f97\u6211\u5011\u80fd\u5920\u5728\u4e0d\u6539\u8b8a\u7d50\u679c\u96c6\u7684\u60c5\u6cc1\u4e0b\uff0c\u9032\u884c\u7d2f\u8a08\u3001\u6392\u540d\u7b49\u64cd\u4f5c\u3002<\/p>\n
SELECT employee_id, employee_name, \n       salary, \n       RANK() OVER (ORDER BY salary DESC) AS salary_rank \nFROM employees;\n<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u6211\u5011\u4f7f\u7528RANK()\u7a97\u53e3\u51fd\u6578\u4f86\u70ba\u6bcf\u4f4d\u54e1\u5de5\u7684\u85aa\u6c34\u9032\u884c\u6392\u540d\u3002\u9019\u6a23\u7684\u67e5\u8a62\u80fd\u5920\u8b93\u6211\u5011\u5728\u540c\u4e00\u7d50\u679c\u96c6\u4e2d\u770b\u5230\u6bcf\u4f4d\u54e1\u5de5\u7684\u85aa\u6c34\u53ca\u5176\u6392\u540d\uff0c\u65b9\u4fbf\u9032\u884c\u9032\u4e00\u6b65\u7684\u5206\u6790\u3002<\/p>\n
\u7e3d\u7d50<\/h2>\n
DB2\u6578\u64da\u5eab\u7684SELECT\u8a9e\u53e5\u63d0\u4f9b\u4e86\u591a\u7a2e\u9ad8\u7d1a\u7528\u6cd5\uff0c\u80fd\u5920\u5e6b\u52a9\u958b\u767c\u8005\u66f4\u9748\u6d3b\u5730\u6aa2\u7d22\u548c\u5206\u6790\u6578\u64da\u3002\u901a\u904e\u4f7f\u7528\u5b50\u67e5\u8a62\u3001\u806f\u63a5\u548c\u7a97\u53e3\u51fd\u6578\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u5728\u8907\u96dc\u7684\u6578\u64da\u74b0\u5883\u4e2d\u9ad8\u6548\u5730\u5de5\u4f5c\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\u82e5\u60a8\u5c0d\u65bc\u9999\u6e2fVPS<\/a><\/code>\u6216\u9999\u6e2f\u4f3a\u670d\u5668<\/a><\/code>\u6709\u8208\u8da3\uff0c\u8acb\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4ee5\u7372\u53d6\u66f4\u591a\u4fe1\u606f\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\uff0c\u512a\u5316\u6578\u64da\u8655\u7406\uff0c\u5be6\u73fe\u66f4\u7cbe\u78ba\u7684\u6578\u64da\u5206\u6790\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-60651","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/60651","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=60651"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/60651\/revisions"}],"predecessor-version":[{"id":60652,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/60651\/revisions\/60652"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=60651"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=60651"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=60651"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}