{"id":95172,"date":"2024-10-19T22:50:23","date_gmt":"2024-10-19T14:50:23","guid":{"rendered":"https:\/\/server.hk\/cnblog\/95172\/"},"modified":"2024-10-19T22:50:24","modified_gmt":"2024-10-19T14:50:24","slug":"oracle%e5%87%bd%e6%95%b8%e4%b8%ad%e7%9a%84%e5%85%a9%e5%a4%a7%e5%87%bd%e6%95%b8%e7%b0%a1%e4%bb%8b","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/95172\/","title":{"rendered":"Oracle\u51fd\u6578\u4e2d\u7684\u5169\u5927\u51fd\u6578\u7c21\u4ecb"},"content":{"rendered":"

Oracle\u51fd\u6578\u4e2d\u7684\u5169\u5927\u51fd\u6578\u7c21\u4ecb<\/h1>\n

\u5728Oracle\u6578\u64da\u5eab\u4e2d\uff0c\u51fd\u6578\u662f\u7528\u4f86\u57f7\u884c\u7279\u5b9a\u64cd\u4f5c\u7684\u9810\u5b9a\u7fa9\u7a0b\u5e8f\u3002\u9019\u4e9b\u51fd\u6578\u53ef\u4ee5\u5e6b\u52a9\u7528\u6236\u9032\u884c\u6578\u64da\u8655\u7406\u3001\u8a08\u7b97\u548c\u8f49\u63db\u7b49\u591a\u7a2e\u4efb\u52d9\u3002\u672c\u6587\u5c07\u4ecb\u7d39Oracle\u4e2d\u5169\u500b\u91cd\u8981\u7684\u51fd\u6578\uff1aNVL<\/strong>\u548cDECODE<\/strong>\u3002<\/p>\n

1. NVL\u51fd\u6578<\/h2>\n

NVL<\/strong>\u51fd\u6578\u662f\u4e00\u500b\u975e\u5e38\u5be6\u7528\u7684\u51fd\u6578\uff0c\u7528\u65bc\u8655\u7406NULL\u503c\u3002\u7576\u6578\u64da\u5eab\u4e2d\u7684\u67d0\u500b\u5b57\u6bb5\u70baNULL\u6642\uff0c\u4f7f\u7528NVL\u51fd\u6578\u53ef\u4ee5\u5c07\u5176\u66ff\u63db\u70ba\u6307\u5b9a\u7684\u503c\u3002\u9019\u5728\u9032\u884c\u6578\u64da\u67e5\u8a62\u548c\u5831\u544a\u6642\u7279\u5225\u6709\u7528\uff0c\u56e0\u70baNULL\u503c\u53ef\u80fd\u6703\u5c0e\u81f4\u8a08\u7b97\u932f\u8aa4\u6216\u4e0d\u5b8c\u6574\u7684\u7d50\u679c\u3002<\/p>\n

\u8a9e\u6cd5<\/h3>\n
NVL(expression1, expression2)<\/code><\/pre>\n
\u5728\u9019\u88e1\uff0cexpression1<\/code>\u662f\u8981\u6aa2\u67e5\u7684\u503c\uff0c\u5982\u679c\u5b83\u662fNULL\uff0c\u5247\u8fd4\u56deexpression2<\/code>\u7684\u503c\u3002<\/p>\n
\u793a\u4f8b<\/h3>\n
\u5047\u8a2d\u6709\u4e00\u500b\u540d\u70baemployees<\/code>\u7684\u8868\uff0c\u5176\u4e2d\u6709\u4e00\u500b\u5b57\u6bb5commission_pct<\/code>\uff0c\u7528\u4f86\u8868\u793a\u54e1\u5de5\u7684\u4f63\u91d1\u767e\u5206\u6bd4\u3002\u5982\u679c\u67d0\u4e9b\u54e1\u5de5\u7684\u4f63\u91d1\u70baNULL\uff0c\u6211\u5011\u53ef\u4ee5\u4f7f\u7528NVL\u51fd\u6578\u5c07\u5176\u66ff\u63db\u70ba0\uff1a<\/p>\n
SELECT employee_id, NVL(commission_pct, 0) AS commission\nFROM employees;<\/code><\/pre>\n
\u9019\u6a23\uff0c\u67e5\u8a62\u7d50\u679c\u4e2d\u6240\u6709NULL\u7684\u4f63\u91d1\u5c07\u986f\u793a\u70ba0\uff0c\u4fbf\u65bc\u5f8c\u7e8c\u7684\u8a08\u7b97\u548c\u5206\u6790\u3002<\/p>\n
2. DECODE\u51fd\u6578<\/h2>\n
DECODE<\/strong>\u51fd\u6578\u662f\u4e00\u7a2e\u689d\u4ef6\u51fd\u6578\uff0c\u985e\u4f3c\u65bc\u5176\u4ed6\u7de8\u7a0b\u8a9e\u8a00\u4e2d\u7684switch-case\u8a9e\u53e5\u3002\u5b83\u53ef\u4ee5\u6839\u64da\u7d66\u5b9a\u7684\u689d\u4ef6\u8fd4\u56de\u4e0d\u540c\u7684\u503c\uff0c\u9019\u4f7f\u5f97\u5728\u67e5\u8a62\u4e2d\u9032\u884c\u689d\u4ef6\u5224\u65b7\u8b8a\u5f97\u66f4\u52a0\u7c21\u55ae\u3002<\/p>\n
\u8a9e\u6cd5<\/h3>\n
DECODE(expression, search, result, ..., default)<\/code><\/pre>\n
\u5728\u9019\u88e1\uff0cexpression<\/code>\u662f\u8981\u6aa2\u67e5\u7684\u503c\uff0csearch<\/code>\u662f\u8981\u5339\u914d\u7684\u503c\uff0cresult<\/code>\u662f\u5339\u914d\u6642\u8fd4\u56de\u7684\u7d50\u679c\u3002\u5982\u679c\u6c92\u6709\u5339\u914d\u7684\u503c\uff0c\u5247\u8fd4\u56dedefault<\/code>\u3002<\/p>\n
\u793a\u4f8b<\/h3>\n
\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70baorders<\/code>\u7684\u8868\uff0c\u5176\u4e2d\u6709\u4e00\u500b\u5b57\u6bb5status<\/code>\uff0c\u7528\u4f86\u8868\u793a\u8a02\u55ae\u7684\u72c0\u614b\u3002\u6211\u5011\u53ef\u4ee5\u4f7f\u7528DECODE\u51fd\u6578\u5c07\u72c0\u614b\u8f49\u63db\u70ba\u66f4\u6613\u65bc\u7406\u89e3\u7684\u63cf\u8ff0\uff1a<\/p>\n
SELECT order_id, DECODE(status, 'P', '\u8655\u7406\u4e2d', 'S', '\u5df2\u767c\u8ca8', 'C', '\u5df2\u53d6\u6d88', '\u672a\u77e5') AS status_description\nFROM orders;<\/code><\/pre>\n
\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u6839\u64dastatus<\/code>\u7684\u503c\uff0c\u67e5\u8a62\u5c07\u8fd4\u56de\u76f8\u61c9\u7684\u63cf\u8ff0\uff0c\u9019\u6a23\u7528\u6236\u53ef\u4ee5\u66f4\u6e05\u695a\u5730\u4e86\u89e3\u6bcf\u500b\u8a02\u55ae\u7684\u72c0\u614b\u3002<\/p>\n
\u7e3d\u7d50<\/h2>\n
\u5728Oracle\u6578\u64da\u5eab\u4e2d\uff0cNVL<\/strong>\u548cDECODE<\/strong>\u51fd\u6578\u662f\u975e\u5e38\u91cd\u8981\u7684\u5de5\u5177\uff0c\u80fd\u5920\u5e6b\u52a9\u7528\u6236\u6709\u6548\u5730\u8655\u7406NULL\u503c\u548c\u9032\u884c\u689d\u4ef6\u5224\u65b7\u3002\u9019\u4e9b\u51fd\u6578\u4e0d\u50c5\u63d0\u9ad8\u4e86\u67e5\u8a62\u7684\u9748\u6d3b\u6027\uff0c\u9084\u589e\u5f37\u4e86\u6578\u64da\u7684\u53ef\u8b80\u6027\u3002\u5c0d\u65bc\u9700\u8981\u9032\u884c\u8907\u96dc\u6578\u64da\u8655\u7406\u7684\u7528\u6236\u4f86\u8aaa\uff0c\u638c\u63e1\u9019\u4e9b\u51fd\u6578\u662f\u975e\u5e38\u5fc5\u8981\u7684\u3002<\/p>\n
\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684\u6578\u64da\u8655\u7406\u89e3\u6c7a\u65b9\u6848\uff0c\u8003\u616e\u4f7f\u7528\u9999\u6e2fVPS<\/a>\u4f86\u652f\u6301\u60a8\u7684Oracle\u6578\u64da\u5eab\u904b\u884c\uff0c\u63d0\u4f9b\u7a69\u5b9a\u7684\u6027\u80fd\u548c\u9748\u6d3b\u7684\u8cc7\u6e90\u914d\u7f6e\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u4e86\u89e3Oracle\u51fd\u6578\u4e2d\u7684\u5169\u5927\u51fd\u6578\uff0c\u63a2\u7d22\u5176\u529f\u80fd\u8207\u61c9\u7528\uff0c\u63d0\u5347\u6578\u64da\u8655\u7406\u6548\u7387\uff0c\u52a9\u529b\u6578\u64da\u5206\u6790\u8207\u7ba1\u7406\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-95172","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/95172","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=95172"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/95172\/revisions"}],"predecessor-version":[{"id":95173,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/95172\/revisions\/95173"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=95172"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=95172"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=95172"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}