{"id":93962,"date":"2024-10-19T18:23:16","date_gmt":"2024-10-19T10:23:16","guid":{"rendered":"https:\/\/server.hk\/cnblog\/93962\/"},"modified":"2024-10-19T18:23:16","modified_gmt":"2024-10-19T10:23:16","slug":"oracle-nvl%e5%87%bd%e6%95%b8%e7%9a%84%e6%ad%a3%e7%a2%ba%e7%94%a8%e6%b3%95","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/93962\/","title":{"rendered":"Oracle Nvl\u51fd\u6578\u7684\u6b63\u78ba\u7528\u6cd5"},"content":{"rendered":"<h1 id=\"oracle-nvl%e5%87%bd%e6%95%b8%e7%9a%84%e6%ad%a3%e7%a2%ba%e7%94%a8%e6%b3%95-bjsqRRgvCc\">Oracle NVL\u51fd\u6578\u7684\u6b63\u78ba\u7528\u6cd5<\/h1>\n<p>\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\u8868\u793a\u7f3a\u5931\u6216\u672a\u77e5\u7684\u6578\u64da\uff0c\u9019\u53ef\u80fd\u6703\u5728\u67e5\u8a62\u548c\u8a08\u7b97\u4e2d\u5f15\u8d77\u554f\u984c\u3002NVL\u51fd\u6578\u7684\u4e3b\u8981\u529f\u80fd\u662f\u5c07NULL\u503c\u66ff\u63db\u70ba\u6307\u5b9a\u7684\u66ff\u4ee3\u503c\uff0c\u5f9e\u800c\u78ba\u4fdd\u6578\u64da\u7684\u5b8c\u6574\u6027\u548c\u6e96\u78ba\u6027\u3002<\/p>\n<h2 id=\"nvl%e5%87%bd%e6%95%b8%e7%9a%84%e8%aa%9e%e6%b3%95-bjsqRRgvCc\">NVL\u51fd\u6578\u7684\u8a9e\u6cd5<\/h2>\n<p>NVL\u51fd\u6578\u7684\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>NVL(expression1, expression2)<\/code><\/pre>\n<p>\u5728\u9019\u88e1\uff0c<code>expression1<\/code>\u662f\u8981\u6aa2\u67e5\u7684\u503c\uff0c\u5982\u679c\u5b83\u662fNULL\uff0c\u5247\u8fd4\u56de<code>expression2<\/code>\u7684\u503c\u3002\u5426\u5247\uff0c\u8fd4\u56de<code>expression1<\/code>\u7684\u503c\u3002<\/p>\n<h2 id=\"nvl%e5%87%bd%e6%95%b8%e7%9a%84%e4%bd%bf%e7%94%a8%e7%af%84%e4%be%8b-bjsqRRgvCc\">NVL\u51fd\u6578\u7684\u4f7f\u7528\u7bc4\u4f8b<\/h2>\n<p>\u4ee5\u4e0b\u662f\u4e00\u4e9b\u4f7f\u7528NVL\u51fd\u6578\u7684\u7bc4\u4f8b\uff1a<\/p>\n<h3 id=\"%e7%af%84%e4%be%8b1%ef%bc%9a%e5%9f%ba%e6%9c%ac%e7%94%a8%e6%b3%95-bjsqRRgvCc\">\u7bc4\u4f8b1\uff1a\u57fa\u672c\u7528\u6cd5<\/h3>\n<p>\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba<code>employees<\/code>\u7684\u8868\u683c\uff0c\u5176\u4e2d\u5305\u542b\u54e1\u5de5\u7684\u85aa\u6c34\u8cc7\u8a0a\u3002\u67d0\u4e9b\u54e1\u5de5\u7684\u85aa\u6c34\u53ef\u80fd\u70baNULL\u3002\u4ee5\u4e0b\u67e5\u8a62\u5c07\u4f7f\u7528NVL\u51fd\u6578\u4f86\u66ff\u63dbNULL\u85aa\u6c34\u70ba0\uff1a<\/p>\n<pre><code>SELECT employee_id, NVL(salary, 0) AS salary\nFROM employees;<\/code><\/pre>\n<p>\u9019\u6a23\uff0c\u5982\u679c\u67d0\u4f4d\u54e1\u5de5\u7684\u85aa\u6c34\u70baNULL\uff0c\u67e5\u8a62\u7d50\u679c\u4e2d\u5c07\u986f\u793a\u70ba0\u3002<\/p>\n<h3 id=\"%e7%af%84%e4%be%8b2%ef%bc%9a%e8%88%87%e5%85%b6%e4%bb%96%e5%87%bd%e6%95%b8%e7%b5%90%e5%90%88%e4%bd%bf%e7%94%a8-bjsqRRgvCc\">\u7bc4\u4f8b2\uff1a\u8207\u5176\u4ed6\u51fd\u6578\u7d50\u5408\u4f7f\u7528<\/h3>\n<p>NVL\u51fd\u6578\u4e5f\u53ef\u4ee5\u8207\u5176\u4ed6\u51fd\u6578\u7d50\u5408\u4f7f\u7528\u3002\u4f8b\u5982\uff0c\u5047\u8a2d\u6211\u5011\u60f3\u8981\u8a08\u7b97\u6bcf\u4f4d\u54e1\u5de5\u7684\u5e74\u85aa\uff0c\u4e26\u5c07NULL\u85aa\u6c34\u66ff\u63db\u70ba0\uff1a<\/p>\n<pre><code>SELECT employee_id, NVL(salary, 0) * 12 AS annual_salary\nFROM employees;<\/code><\/pre>\n<p>\u9019\u6a23\uff0c\u5373\u4f7f\u67d0\u4f4d\u54e1\u5de5\u7684\u85aa\u6c34\u70baNULL\uff0c\u5e74\u85aa\u8a08\u7b97\u4e5f\u4e0d\u6703\u51fa\u73fe\u932f\u8aa4\u3002<\/p>\n<h2 id=\"nvl%e5%87%bd%e6%95%b8%e7%9a%84%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-bjsqRRgvCc\">NVL\u51fd\u6578\u7684\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5728\u4f7f\u7528NVL\u51fd\u6578\u6642\uff0c\u6709\u5e7e\u9ede\u9700\u8981\u6ce8\u610f\uff1a<\/p>\n<ul>\n<li><strong>\u6578\u64da\u985e\u578b\u4e00\u81f4\u6027\uff1a<\/strong>NVL\u51fd\u6578\u7684\u5169\u500b\u53c3\u6578\u5fc5\u9808\u662f\u76f8\u540c\u7684\u6578\u64da\u985e\u578b\u3002\u5982\u679c\u4e0d\u4e00\u81f4\uff0cOracle\u6703\u81ea\u52d5\u9032\u884c\u985e\u578b\u8f49\u63db\uff0c\u4f46\u9019\u53ef\u80fd\u6703\u5c0e\u81f4\u6027\u80fd\u554f\u984c\u3002<\/li>\n<li><strong>\u6027\u80fd\u8003\u91cf\uff1a<\/strong>\u5728\u5927\u578b\u6578\u64da\u96c6\u4e0a\u4f7f\u7528NVL\u51fd\u6578\u6642\uff0c\u53ef\u80fd\u6703\u5f71\u97ff\u67e5\u8a62\u6027\u80fd\u3002\u5efa\u8b70\u5728\u5fc5\u8981\u6642\u4f7f\u7528\uff0c\u4e26\u8003\u616e\u5176\u4ed6\u66ff\u4ee3\u65b9\u6848\uff0c\u5982COALESCE\u51fd\u6578\u3002<\/li>\n<li><strong>NULL\u7684\u610f\u7fa9\uff1a<\/strong>\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0cNULL\u503c\u53ef\u80fd\u5177\u6709\u7279\u5b9a\u7684\u696d\u52d9\u610f\u7fa9\u3002\u5728\u9019\u7a2e\u60c5\u6cc1\u4e0b\uff0c\u4f7f\u7528NVL\u51fd\u6578\u66ff\u63dbNULL\u503c\u53ef\u80fd\u6703\u5c0e\u81f4\u6578\u64da\u89e3\u91cb\u4e0a\u7684\u8aa4\u5dee\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b5%90%e8%ab%96-bjsqRRgvCc\">\u7d50\u8ad6<\/h2>\n<p>NVL\u51fd\u6578\u5728Oracle\u8cc7\u6599\u5eab\u4e2d\u662f\u4e00\u500b\u5f37\u5927\u7684\u5de5\u5177\uff0c\u80fd\u5920\u6709\u6548\u5730\u8655\u7406NULL\u503c\uff0c\u78ba\u4fdd\u67e5\u8a62\u548c\u8a08\u7b97\u7684\u6e96\u78ba\u6027\u3002\u901a\u904e\u6b63\u78ba\u4f7f\u7528NVL\u51fd\u6578\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u63d0\u9ad8\u6578\u64da\u7684\u5b8c\u6574\u6027\uff0c\u4e26\u6e1b\u5c11\u56e0NULL\u503c\u5f15\u8d77\u7684\u932f\u8aa4\u3002\u5728\u5be6\u969b\u61c9\u7528\u4e2d\uff0c\u958b\u767c\u8005\u61c9\u6839\u64da\u5177\u9ad4\u9700\u6c42\u9078\u64c7\u5408\u9069\u7684\u51fd\u6578\uff0c\u4e26\u8003\u616e\u6027\u80fd\u548c\u6578\u64da\u985e\u578b\u7684\u4e00\u81f4\u6027\u3002<\/p>\n<p>\u5982\u9700\u4e86\u89e3\u66f4\u591a\u95dc\u65bc<code>VPS<\/code>\u3001<code>\u9999\u6e2fVPS<\/code>\u53ca\u5176\u4ed6<code>\u4f3a\u670d\u5668<\/code>\u7684\u8cc7\u8a0a\uff0c\u8acb\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9 <a href=\"https:\/\/server.hk\">Server.HK<\/a>\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3Oracle NVL\u51fd\u6578\u7684\u6b63\u78ba\u7528\u6cd5\uff0c\u5b78\u7fd2\u5982\u4f55\u8655\u7406NULL\u503c\u4ee5\u63d0\u9ad8\u6578\u64da\u67e5\u8a62\u7684\u6e96\u78ba\u6027\u548c\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-93962","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/93962","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=93962"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/93962\/revisions"}],"predecessor-version":[{"id":93963,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/93962\/revisions\/93963"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=93962"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=93962"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=93962"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}