{"id":93892,"date":"2024-10-19T17:47:19","date_gmt":"2024-10-19T09:47:19","guid":{"rendered":"https:\/\/server.hk\/cnblog\/93892\/"},"modified":"2024-10-19T17:47:20","modified_gmt":"2024-10-19T09:47:20","slug":"oracle-decode%e5%87%bd%e6%95%b8%e5%92%8ccase%e8%aa%9e%e5%8f%a5%e7%9a%84%e6%af%94%e8%bc%83","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/93892\/","title":{"rendered":"Oracle Decode()\u51fd\u6578\u548cCASE\u8a9e\u53e5\u7684\u6bd4\u8f03"},"content":{"rendered":"<h1 id=\"oracle-decode%e5%87%bd%e6%95%b8%e5%92%8ccase%e8%aa%9e%e5%8f%a5%e7%9a%84%e6%af%94%e8%bc%83-MPJtEQfVtG\">Oracle Decode()\u51fd\u6578\u548cCASE\u8a9e\u53e5\u7684\u6bd4\u8f03<\/h1>\n<p>\u5728Oracle\u6578\u64da\u5eab\u4e2d\uff0c<code>DECODE()<\/code>\u51fd\u6578\u548c<code>CASE<\/code>\u8a9e\u53e5\u90fd\u662f\u7528\u4f86\u9032\u884c\u689d\u4ef6\u5224\u65b7\u7684\u5de5\u5177\u3002\u96d6\u7136\u5b83\u5011\u7684\u529f\u80fd\u76f8\u4f3c\uff0c\u4f46\u5728\u8a9e\u6cd5\u3001\u53ef\u8b80\u6027\u548c\u4f7f\u7528\u5834\u666f\u4e0a\u537b\u5b58\u5728\u4e00\u4e9b\u5dee\u7570\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e\u9019\u5169\u8005\u7684\u7279\u9ede\uff0c\u4e26\u63d0\u4f9b\u76f8\u61c9\u7684\u793a\u4f8b\uff0c\u4ee5\u5e6b\u52a9\u8b80\u8005\u66f4\u597d\u5730\u7406\u89e3\u5b83\u5011\u7684\u4f7f\u7528\u3002<\/p>\n<h2 id=\"decode%e5%87%bd%e6%95%b8-MPJtEQfVtG\">DECODE()\u51fd\u6578<\/h2>\n<p><code>DECODE()<\/code>\u51fd\u6578\u662f\u4e00\u7a2e\u7c21\u55ae\u7684\u689d\u4ef6\u5224\u65b7\u51fd\u6578\uff0c\u901a\u5e38\u7528\u65bc\u5c07\u4e00\u500b\u8868\u9054\u5f0f\u7684\u503c\u8207\u4e00\u7cfb\u5217\u53ef\u80fd\u7684\u503c\u9032\u884c\u6bd4\u8f03\u3002\u5176\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>DECODE(expression, search_1, result_1, search_2, result_2, ..., default_result)<\/code><\/pre>\n<p>\u5728\u9019\u88e1\uff0c<code>expression<\/code>\u662f\u8981\u9032\u884c\u6bd4\u8f03\u7684\u503c\uff0c<code>search_n<\/code>\u662f\u8981\u6bd4\u8f03\u7684\u503c\uff0c\u800c<code>result_n<\/code>\u662f\u7576<code>expression<\/code>\u7b49\u65bc<code>search_n<\/code>\u6642\u8fd4\u56de\u7684\u7d50\u679c\u3002\u5982\u679c\u6c92\u6709\u5339\u914d\u7684\u503c\uff0c\u5247\u8fd4\u56de<code>default_result<\/code>\u3002<\/p>\n<h3 id=\"decode%e5%87%bd%e6%95%b8%e7%a4%ba%e4%be%8b-MPJtEQfVtG\">DECODE()\u51fd\u6578\u793a\u4f8b<\/h3>\n<p>\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528<code>DECODE()<\/code>\u51fd\u6578\u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code>SELECT employee_id, \n       DECODE(department_id, \n              10, '\u884c\u653f\u90e8', \n              20, '\u92b7\u552e\u90e8', \n              30, '\u6280\u8853\u90e8', \n              '\u5176\u4ed6\u90e8\u9580') AS department_name\nFROM employees;<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u6839\u64da<code>department_id<\/code>\u7684\u503c\uff0c\u67e5\u8a62\u5c07\u8fd4\u56de\u76f8\u61c9\u7684\u90e8\u9580\u540d\u7a31\u3002\u5982\u679c<code>department_id<\/code>\u7684\u503c\u4e0d\u5728\u6307\u5b9a\u7684\u7bc4\u570d\u5167\uff0c\u5247\u8fd4\u56de\u201c\u5176\u4ed6\u90e8\u9580\u201d\u3002<\/p>\n<h2 id=\"case%e8%aa%9e%e5%8f%a5-MPJtEQfVtG\">CASE\u8a9e\u53e5<\/h2>\n<p><code>CASE<\/code>\u8a9e\u53e5\u662f\u4e00\u7a2e\u66f4\u9748\u6d3b\u7684\u689d\u4ef6\u5224\u65b7\u5de5\u5177\uff0c\u652f\u6301\u591a\u7a2e\u689d\u4ef6\u5224\u65b7\u65b9\u5f0f\u3002\u5176\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>CASE \n    WHEN condition_1 THEN result_1\n    WHEN condition_2 THEN result_2\n    ...\n    ELSE default_result\nEND<\/code><\/pre>\n<p>\u5728\u9019\u88e1\uff0c<code>condition_n<\/code>\u662f\u8981\u8a55\u4f30\u7684\u689d\u4ef6\uff0c\u7576\u67d0\u500b\u689d\u4ef6\u70ba\u771f\u6642\uff0c\u5c07\u8fd4\u56de\u76f8\u61c9\u7684\u7d50\u679c\u3002\u5982\u679c\u6240\u6709\u689d\u4ef6\u90fd\u4e0d\u6eff\u8db3\uff0c\u5247\u8fd4\u56de<code>default_result<\/code>\u3002<\/p>\n<h3 id=\"case%e8%aa%9e%e5%8f%a5%e7%a4%ba%e4%be%8b-MPJtEQfVtG\">CASE\u8a9e\u53e5\u793a\u4f8b<\/h3>\n<p>\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528<code>CASE<\/code>\u8a9e\u53e5\u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code>SELECT employee_id, \n       CASE \n           WHEN department_id = 10 THEN '\u884c\u653f\u90e8'\n           WHEN department_id = 20 THEN '\u92b7\u552e\u90e8'\n           WHEN department_id = 30 THEN '\u6280\u8853\u90e8'\n           ELSE '\u5176\u4ed6\u90e8\u9580'\n       END AS department_name\nFROM employees;<\/code><\/pre>\n<p>\u9019\u500b\u4f8b\u5b50\u8207\u524d\u9762\u7684<code>DECODE()<\/code>\u793a\u4f8b\u76f8\u4f3c\uff0c\u4f46\u4f7f\u7528\u4e86<code>CASE<\/code>\u8a9e\u53e5\u4f86\u9032\u884c\u689d\u4ef6\u5224\u65b7\u3002\u9019\u4f7f\u5f97<code>CASE<\/code>\u8a9e\u53e5\u5728\u8655\u7406\u8907\u96dc\u689d\u4ef6\u6642\u66f4\u52a0\u9748\u6d3b\u3002<\/p>\n<h2 id=\"decode%e8%88%87case%e7%9a%84%e6%af%94%e8%bc%83-MPJtEQfVtG\">DECODE()\u8207CASE\u7684\u6bd4\u8f03<\/h2>\n<ul>\n<li><strong>\u53ef\u8b80\u6027\uff1a<\/strong>\u5728\u7c21\u55ae\u7684\u689d\u4ef6\u5224\u65b7\u4e2d\uff0c<code>DECODE()<\/code>\u51fd\u6578\u7684\u53ef\u8b80\u6027\u8f03\u9ad8\uff0c\u4f46\u7576\u689d\u4ef6\u8b8a\u5f97\u8907\u96dc\u6642\uff0c<code>CASE<\/code>\u8a9e\u53e5\u7684\u53ef\u8b80\u6027\u66f4\u4f73\u3002<\/li>\n<li><strong>\u9748\u6d3b\u6027\uff1a<\/strong><code>CASE<\/code>\u8a9e\u53e5\u652f\u6301\u66f4\u8907\u96dc\u7684\u908f\u8f2f\u904b\u7b97\uff0c\u4f8b\u5982\u4f7f\u7528\u5e03\u723e\u904b\u7b97\u7b26\uff0c\u800c<code>DECODE()<\/code>\u51fd\u6578\u5247\u50c5\u652f\u6301\u7b49\u503c\u6bd4\u8f03\u3002<\/li>\n<li><strong>\u6027\u80fd\uff1a<\/strong>\u5728\u6027\u80fd\u65b9\u9762\uff0c\u5169\u8005\u7684\u5dee\u7570\u901a\u5e38\u4e0d\u5927\uff0c\u4f46\u5177\u9ad4\u60c5\u6cc1\u53d6\u6c7a\u65bc\u67e5\u8a62\u7684\u8907\u96dc\u6027\u548c\u6578\u64da\u91cf\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-MPJtEQfVtG\">\u7e3d\u7d50<\/h2>\n<p>\u7e3d\u7684\u4f86\u8aaa\uff0c<code>DECODE()<\/code>\u51fd\u6578\u548c<code>CASE<\/code>\u8a9e\u53e5\u5404\u6709\u5176\u512a\u7f3a\u9ede\u3002\u9078\u64c7\u4f7f\u7528\u54ea\u4e00\u7a2e\u5de5\u5177\u53d6\u6c7a\u65bc\u5177\u9ad4\u7684\u9700\u6c42\u548c\u60c5\u5883\u3002\u5728\u7c21\u55ae\u7684\u689d\u4ef6\u5224\u65b7\u4e2d\uff0c<code>DECODE()<\/code>\u51fd\u6578\u53ef\u80fd\u66f4\u70ba\u65b9\u4fbf\uff0c\u800c\u5728\u9700\u8981\u8655\u7406\u8907\u96dc\u908f\u8f2f\u6642\uff0c<code>CASE<\/code>\u8a9e\u53e5\u5247\u66f4\u5177\u512a\u52e2\u3002<\/p>\n<p>\u5982\u679c\u60a8\u5c0d\u65bc\u6578\u64da\u5eab\u7ba1\u7406\u548c\u67e5\u8a62\u512a\u5316\u6709\u9032\u4e00\u6b65\u7684\u9700\u6c42\uff0c\u8003\u616e\u4f7f\u7528\u6211\u5011\u7684<a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a>\u89e3\u6c7a\u65b9\u6848\uff0c\u4ee5\u7372\u5f97\u66f4\u9ad8\u6548\u7684\u6578\u64da\u8655\u7406\u80fd\u529b\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u6bd4\u8f03Oracle Decode()\u51fd\u6578\u8207CASE\u8a9e\u53e5\u7684\u529f\u80fd\u3001\u7528\u6cd5\u53ca\u6027\u80fd\uff0c\u5e6b\u52a9\u958b\u767c\u8005\u9078\u64c7\u6700\u4f73\u89e3\u6c7a\u65b9\u6848\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-93892","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/93892","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=93892"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/93892\/revisions"}],"predecessor-version":[{"id":93893,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/93892\/revisions\/93893"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=93892"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=93892"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=93892"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}