{"id":93960,"date":"2024-10-19T18:22:16","date_gmt":"2024-10-19T10:22:16","guid":{"rendered":"https:\/\/server.hk\/cnblog\/93960\/"},"modified":"2024-10-19T18:22:17","modified_gmt":"2024-10-19T10:22:17","slug":"oracle-nvl%e5%87%bd%e6%95%b8%e7%9a%84%e5%af%a6%e9%9a%9b%e6%87%89%e7%94%a8%e6%9c%89%e5%93%aa%e4%ba%9b%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/93960\/","title":{"rendered":"Oracle Nvl\u51fd\u6578\u7684\u5be6\u969b\u61c9\u7528\u6709\u54ea\u4e9b\uff1f"},"content":{"rendered":"

Oracle NVL\u51fd\u6578\u7684\u5be6\u969b\u61c9\u7528\u6709\u54ea\u4e9b\uff1f<\/h1>\n

\u5728Oracle\u8cc7\u6599\u5eab\u4e2d\uff0cNVL\u51fd\u6578\u662f\u4e00\u500b\u975e\u5e38\u5be6\u7528\u7684\u5de5\u5177\uff0c\u4e3b\u8981\u7528\u65bc\u8655\u7406NULL\u503c\u3002NULL\u503c\u5728\u8cc7\u6599\u5eab\u4e2d\u4ee3\u8868\u7f3a\u5931\u6216\u672a\u77e5\u7684\u6578\u64da\uff0c\u9019\u53ef\u80fd\u6703\u5c0d\u6578\u64da\u5206\u6790\u548c\u5831\u544a\u9020\u6210\u56f0\u64fe\u3002NVL\u51fd\u6578\u7684\u4e3b\u8981\u529f\u80fd\u662f\u5c07NULL\u503c\u66ff\u63db\u70ba\u6307\u5b9a\u7684\u66ff\u4ee3\u503c\uff0c\u5f9e\u800c\u4f7f\u6578\u64da\u66f4\u5177\u53ef\u8b80\u6027\u548c\u53ef\u7528\u6027\u3002<\/p>\n

NVL\u51fd\u6578\u7684\u57fa\u672c\u8a9e\u6cd5<\/h2>\n

NVL\u51fd\u6578\u7684\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\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\u5426\u5247\uff0c\u8fd4\u56deexpression1<\/code>\u7684\u503c\u3002<\/p>\n
NVL\u51fd\u6578\u7684\u5be6\u969b\u61c9\u7528<\/h2>\n
1. \u6578\u64da\u6e05\u7406<\/h3>\n
\u5728\u6578\u64da\u5206\u6790\u4e2d\uff0c\u7d93\u5e38\u6703\u9047\u5230NULL\u503c\u3002\u4f7f\u7528NVL\u51fd\u6578\u53ef\u4ee5\u5728\u67e5\u8a62\u4e2d\u6e05\u7406\u9019\u4e9b\u6578\u64da\u3002\u4f8b\u5982\uff0c\u5047\u8a2d\u6709\u4e00\u500b\u54e1\u5de5\u8868\uff0c\u5176\u4e2d\u67d0\u4e9b\u54e1\u5de5\u7684\u734e\u91d1\u70baNULL\uff0c\u60a8\u5e0c\u671b\u5728\u5831\u544a\u4e2d\u986f\u793a\u734e\u91d1\u70ba0\u800c\u4e0d\u662fNULL\uff1a<\/p>\n
SELECT employee_id, NVL(bonus, 0) AS bonus\nFROM employees;<\/code><\/pre>\n
\u9019\u6a23\uff0c\u6240\u6709NULL\u7684\u734e\u91d1\u5c07\u986f\u793a\u70ba0\uff0c\u4fbf\u65bc\u5f8c\u7e8c\u7684\u6578\u64da\u5206\u6790\u3002<\/p>\n
2. \u5831\u544a\u751f\u6210<\/h3>\n
\u5728\u751f\u6210\u5831\u544a\u6642\uff0cNULL\u503c\u53ef\u80fd\u6703\u5c0e\u81f4\u5831\u544a\u7684\u53ef\u8b80\u6027\u4e0b\u964d\u3002\u4f7f\u7528NVL\u51fd\u6578\u53ef\u4ee5\u78ba\u4fdd\u5831\u544a\u4e2d\u7684\u6240\u6709\u6578\u64da\u90fd\u662f\u5b8c\u6574\u7684\u3002\u4f8b\u5982\uff0c\u60a8\u53ef\u4ee5\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528NVL\u4f86\u986f\u793a\u5ba2\u6236\u7684\u96fb\u8a71\u865f\u78bc\uff0c\u5982\u679c\u96fb\u8a71\u865f\u78bc\u70baNULL\uff0c\u5247\u986f\u793a\u201c\u7121\u96fb\u8a71\u865f\u78bc\u201d\uff1a<\/p>\n
SELECT customer_id, NVL(phone, '\u7121\u96fb\u8a71\u865f\u78bc') AS phone\nFROM customers;<\/code><\/pre>\n
3. \u6578\u64da\u805a\u5408<\/h3>\n
\u5728\u9032\u884c\u6578\u64da\u805a\u5408\u6642\uff0cNULL\u503c\u53ef\u80fd\u6703\u5f71\u97ff\u8a08\u7b97\u7d50\u679c\u3002\u4f7f\u7528NVL\u51fd\u6578\u53ef\u4ee5\u78ba\u4fdd\u5728\u8a08\u7b97\u7e3d\u548c\u6216\u5e73\u5747\u503c\u6642\u4e0d\u6703\u53d7\u5230NULL\u503c\u7684\u5f71\u97ff\u3002\u4f8b\u5982\uff0c\u8a08\u7b97\u6240\u6709\u54e1\u5de5\u7684\u7e3d\u85aa\u8cc7\u6642\uff0c\u53ef\u4ee5\u4f7f\u7528NVL\u5c07NULL\u85aa\u8cc7\u8996\u70ba0\uff1a<\/p>\n
SELECT SUM(NVL(salary, 0)) AS total_salary\nFROM employees;<\/code><\/pre>\n
4. \u689d\u4ef6\u67e5\u8a62<\/h3>\n
\u5728\u9032\u884c\u689d\u4ef6\u67e5\u8a62\u6642\uff0cNULL\u503c\u53ef\u80fd\u6703\u5c0e\u81f4\u67e5\u8a62\u7d50\u679c\u4e0d\u5b8c\u6574\u3002\u4f7f\u7528NVL\u51fd\u6578\u53ef\u4ee5\u78ba\u4fdd\u67e5\u8a62\u7684\u6b63\u78ba\u6027\u3002\u4f8b\u5982\uff0c\u60a8\u53ef\u4ee5\u67e5\u8a62\u6240\u6709\u54e1\u5de5\u7684\u734e\u91d1\uff0c\u5982\u679c\u734e\u91d1\u70baNULL\uff0c\u5247\u5c07\u5176\u8996\u70ba0\uff1a<\/p>\n
SELECT employee_id\nFROM employees\nWHERE NVL(bonus, 0) > 1000;<\/code><\/pre>\n
\u9019\u6a23\uff0c\u6240\u6709\u734e\u91d1\u70baNULL\u7684\u54e1\u5de5\u5c07\u88ab\u8996\u70ba\u734e\u91d1\u70ba0\uff0c\u5f9e\u800c\u4e0d\u6703\u5f71\u97ff\u67e5\u8a62\u7d50\u679c\u3002<\/p>\n
\u7e3d\u7d50<\/h2>\n
Oracle\u7684NVL\u51fd\u6578\u5728\u6578\u64da\u8655\u7406\u548c\u5206\u6790\u4e2d\u5177\u6709\u5ee3\u6cdb\u7684\u61c9\u7528\uff0c\u80fd\u5920\u6709\u6548\u5730\u8655\u7406NULL\u503c\uff0c\u63d0\u5347\u6578\u64da\u7684\u53ef\u8b80\u6027\u548c\u53ef\u7528\u6027\u3002\u7121\u8ad6\u662f\u5728\u6578\u64da\u6e05\u7406\u3001\u5831\u544a\u751f\u6210\u3001\u6578\u64da\u805a\u5408\u9084\u662f\u689d\u4ef6\u67e5\u8a62\u4e2d\uff0cNVL\u51fd\u6578\u90fd\u80fd\u767c\u63ee\u91cd\u8981\u4f5c\u7528\u3002\u5c0d\u65bc\u9700\u8981\u8655\u7406\u5927\u91cf\u6578\u64da\u7684\u4f01\u696d\u4f86\u8aaa\uff0c\u638c\u63e1NVL\u51fd\u6578\u7684\u4f7f\u7528\u5c07\u6709\u52a9\u65bc\u63d0\u9ad8\u6578\u64da\u5206\u6790\u7684\u6548\u7387\u3002<\/p>\n
\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 \u9999\u6e2fVPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u6eff\u8db3\u60a8\u7684\u9700\u6c42\u3002\u7121\u8ad6\u662f\u6578\u64da\u5eab\u7ba1\u7406\u9084\u662f\u7db2\u7ad9\u6258\u7ba1\uff0c\u6211\u5011\u7684 \u4f3a\u670d\u5668<\/a> \u90fd\u80fd\u70ba\u60a8\u63d0\u4f9b\u7a69\u5b9a\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u63a2\u7d22Oracle NVL\u51fd\u6578\u7684\u5be6\u969b\u61c9\u7528\uff0c\u5305\u62ec\u6578\u64da\u6e05\u7406\u3001\u5831\u544a\u751f\u6210\u53ca\u907f\u514d\u7a7a\u503c\u554f\u984c\uff0c\u63d0\u5347\u6578\u64da\u8655\u7406\u6548\u7387\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-93960","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/93960","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=93960"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/93960\/revisions"}],"predecessor-version":[{"id":93961,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/93960\/revisions\/93961"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=93960"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=93960"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=93960"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}