{"id":60489,"date":"2024-10-13T03:17:15","date_gmt":"2024-10-12T19:17:15","guid":{"rendered":"https:\/\/server.hk\/cnblog\/60489\/"},"modified":"2024-10-13T03:17:15","modified_gmt":"2024-10-12T19:17:15","slug":"db2%e5%88%86%e9%a1%9e%e5%8f%96%e5%89%8dn%e5%80%8b%e8%a8%98%e9%8c%84%e7%9a%84sql%e8%aa%9e%e5%8f%a5","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/60489\/","title":{"rendered":"DB2\u5206\u985e\u53d6\u524dN\u500b\u8a18\u9304\u7684SQL\u8a9e\u53e5"},"content":{"rendered":"<h1 id=\"db2%e5%88%86%e9%a1%9e%e5%8f%96%e5%89%8dn%e5%80%8b%e8%a8%98%e9%8c%84%e7%9a%84sql%e8%aa%9e%e5%8f%a5-djSCIeAPJq\">DB2\u5206\u985e\u53d6\u524dN\u500b\u8a18\u9304\u7684SQL\u8a9e\u53e5<\/h1>\n<p>\u5728\u8cc7\u6599\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0cIBM\u7684DB2\u662f\u4e00\u500b\u5f37\u5927\u7684\u9078\u64c7\uff0c\u7279\u5225\u662f\u5728\u8655\u7406\u5927\u578b\u6578\u64da\u96c6\u6642\u3002\u7576\u6211\u5011\u9700\u8981\u5f9e\u4e00\u500b\u5206\u985e\u4e2d\u63d0\u53d6\u524dN\u500b\u8a18\u9304\u6642\uff0cDB2\u63d0\u4f9b\u4e86\u591a\u7a2e\u65b9\u6cd5\u4f86\u5be6\u73fe\u9019\u4e00\u9700\u6c42\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u5982\u4f55\u5728DB2\u4e2d\u4f7f\u7528SQL\u8a9e\u53e5\u4f86\u9054\u6210\u9019\u4e00\u76ee\u6a19\uff0c\u4e26\u63d0\u4f9b\u76f8\u95dc\u7684\u7bc4\u4f8b\u548c\u89e3\u91cb\u3002<\/p>\n<h2 id=\"%e5%9f%ba%e6%9c%ac%e6%a6%82%e5%bf%b5-djSCIeAPJq\">\u57fa\u672c\u6982\u5ff5<\/h2>\n<p>\u5728DB2\u4e2d\uff0c\u63d0\u53d6\u524dN\u500b\u8a18\u9304\u901a\u5e38\u6d89\u53ca\u5230\u6392\u5e8f\u548c\u9650\u5236\u7d50\u679c\u96c6\u7684\u5927\u5c0f\u3002\u9019\u53ef\u4ee5\u901a\u904e\u4f7f\u7528<code>ROW_NUMBER()<\/code>\u51fd\u6578\u4f86\u5be6\u73fe\uff0c\u9019\u662f\u4e00\u500b\u7a97\u53e3\u51fd\u6578\uff0c\u80fd\u5920\u70ba\u6bcf\u4e00\u884c\u5206\u914d\u4e00\u500b\u552f\u4e00\u7684\u5e8f\u865f\u3002\u9019\u6a23\uff0c\u6211\u5011\u5c31\u53ef\u4ee5\u6839\u64da\u9019\u500b\u5e8f\u865f\u4f86\u9078\u64c7\u524dN\u500b\u8a18\u9304\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8row_number%e5%87%bd%e6%95%b8-djSCIeAPJq\">\u4f7f\u7528ROW_NUMBER()\u51fd\u6578<\/h2>\n<p>\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528<code>ROW_NUMBER()<\/code>\u51fd\u6578\u7684\u7bc4\u4f8b\uff0c\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba<code>employees<\/code>\u7684\u8868\u683c\uff0c\u4e26\u5e0c\u671b\u6839\u64da<code>salary<\/code>\u5b57\u6bb5\u63d0\u53d6\u85aa\u6c34\u6700\u9ad8\u7684\u524d5\u540d\u54e1\u5de5\u3002<\/p>\n<pre><code>\nSELECT *\nFROM (\n    SELECT \n        employee_id, \n        employee_name, \n        salary, \n        ROW_NUMBER() OVER (ORDER BY salary DESC) AS rn\n    FROM employees\n) AS ranked\nWHERE rn &lt;= 5;\n<\/code><\/pre>\n<p>\u5728\u9019\u500b\u7bc4\u4f8b\u4e2d\uff0c\u6211\u5011\u9996\u5148\u4f7f\u7528<code>ROW_NUMBER()<\/code>\u51fd\u6578\u70ba\u6bcf\u4e00\u884c\u5206\u914d\u4e00\u500b\u5e8f\u865f\uff0c\u7136\u5f8c\u5728\u5916\u90e8\u67e5\u8a62\u4e2d\u9078\u64c7\u5e8f\u865f\u5c0f\u65bc\u6216\u7b49\u65bc5\u7684\u8a18\u9304\u3002\u9019\u6a23\uff0c\u6211\u5011\u5c31\u80fd\u5920\u7372\u5f97\u85aa\u6c34\u6700\u9ad8\u7684\u524d5\u540d\u54e1\u5de5\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8fetch-first%e8%aa%9e%e5%8f%a5-djSCIeAPJq\">\u4f7f\u7528FETCH FIRST\u8a9e\u53e5<\/h2>\n<p>\u53e6\u4e00\u7a2e\u65b9\u6cd5\u662f\u4f7f\u7528<code>FETCH FIRST<\/code>\u8a9e\u53e5\uff0c\u9019\u5728DB2 11\u53ca\u4ee5\u5f8c\u7684\u7248\u672c\u4e2d\u53ef\u7528\u3002\u9019\u7a2e\u65b9\u6cd5\u76f8\u5c0d\u7c21\u55ae\uff0c\u9069\u5408\u7528\u65bc\u4e0d\u9700\u8981\u8907\u96dc\u6392\u5e8f\u7684\u60c5\u6cc1\u3002<\/p>\n<pre><code>\nSELECT employee_id, employee_name, salary\nFROM employees\nORDER BY salary DESC\nFETCH FIRST 5 ROWS ONLY;\n<\/code><\/pre>\n<p>\u5728\u9019\u500b\u7bc4\u4f8b\u4e2d\uff0c\u6211\u5011\u540c\u6a23\u662f\u6839\u64da<code>salary<\/code>\u5b57\u6bb5\u9032\u884c\u6392\u5e8f\uff0c\u7136\u5f8c\u4f7f\u7528<code>FETCH FIRST 5 ROWS ONLY<\/code>\u4f86\u9650\u5236\u7d50\u679c\u96c6\u7684\u5927\u5c0f\uff0c\u50c5\u8fd4\u56de\u524d5\u540d\u8a18\u9304\u3002<\/p>\n<h2 id=\"%e5%88%86%e7%b5%84%e5%be%8c%e5%8f%96%e5%89%8dn%e5%80%8b%e8%a8%98%e9%8c%84-djSCIeAPJq\">\u5206\u7d44\u5f8c\u53d6\u524dN\u500b\u8a18\u9304<\/h2>\n<p>\u5982\u679c\u9700\u8981\u5728\u6bcf\u500b\u5206\u985e\u4e2d\u63d0\u53d6\u524dN\u500b\u8a18\u9304\uff0c\u4f8b\u5982\u5728\u6bcf\u500b\u90e8\u9580\u4e2d\u63d0\u53d6\u85aa\u6c34\u6700\u9ad8\u7684\u524d3\u540d\u54e1\u5de5\uff0c\u53ef\u4ee5\u7d50\u5408<code>ROW_NUMBER()<\/code>\u548c<code>PARTITION BY<\/code>\u4f86\u5be6\u73fe\u3002<\/p>\n<pre><code>\nSELECT *\nFROM (\n    SELECT \n        employee_id, \n        employee_name, \n        department_id, \n        salary, \n        ROW_NUMBER() OVER (PARTITION BY department_id ORDER BY salary DESC) AS rn\n    FROM employees\n) AS ranked\nWHERE rn &lt;= 3;\n<\/code><\/pre>\n<p>\u5728\u9019\u500b\u7bc4\u4f8b\u4e2d\uff0c\u6211\u5011\u4f7f\u7528<code>PARTITION BY department_id<\/code>\u4f86\u70ba\u6bcf\u500b\u90e8\u9580\u7684\u54e1\u5de5\u5206\u914d\u5e8f\u865f\uff0c\u7136\u5f8c\u9078\u64c7\u6bcf\u500b\u90e8\u9580\u4e2d\u85aa\u6c34\u6700\u9ad8\u7684\u524d3\u540d\u54e1\u5de5\u3002<\/p>\n<h2 id=\"%e7%b8%bd%e7%b5%90-djSCIeAPJq\">\u7e3d\u7d50<\/h2>\n<p>\u5728DB2\u4e2d\uff0c\u63d0\u53d6\u524dN\u500b\u8a18\u9304\u7684SQL\u8a9e\u53e5\u53ef\u4ee5\u901a\u904e\u591a\u7a2e\u65b9\u5f0f\u5be6\u73fe\uff0c\u5305\u62ec\u4f7f\u7528<code>ROW_NUMBER()<\/code>\u51fd\u6578\u548c<code>FETCH FIRST<\/code>\u8a9e\u53e5\u3002\u9019\u4e9b\u65b9\u6cd5\u4e0d\u50c5\u9748\u6d3b\uff0c\u9084\u80fd\u5920\u61c9\u5c0d\u4e0d\u540c\u7684\u9700\u6c42\uff0c\u5982\u5728\u5206\u7d44\u5f8c\u63d0\u53d6\u8a18\u9304\u7b49\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u6578\u64da\u8655\u7406\u7684\u4f01\u696d\u4f86\u8aaa\uff0c\u638c\u63e1\u9019\u4e9b\u6280\u5de7\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u53ef\u9760\u7684 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u6eff\u8db3\u4e0d\u540c\u7684\u9700\u6c42\u3002\u7121\u8ad6\u662f\u6578\u64da\u5eab\u7ba1\u7406\u9084\u662f\u7db2\u7ad9\u6258\u7ba1\uff0c\u6211\u5011\u7684 <a href=\"https:\/\/server.hk\">\u4f3a\u670d\u5668<\/a> \u90fd\u80fd\u70ba\u60a8\u63d0\u4f9b\u7a69\u5b9a\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u63a2\u7d22DB2\u4e2d\u63d0\u53d6\u524dN\u500b\u8a18\u9304\u7684SQL\u8a9e\u53e5\uff0c\u7c21\u5316\u6578\u64da\u67e5\u8a62\uff0c\u63d0\u5347\u6548\u7387\uff0c\u52a9\u60a8\u5feb\u901f\u7372\u53d6\u6240\u9700\u4fe1\u606f\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-60489","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/60489","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=60489"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/60489\/revisions"}],"predecessor-version":[{"id":60490,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/60489\/revisions\/60490"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=60489"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=60489"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=60489"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}