{"id":160189,"date":"2024-11-03T21:01:16","date_gmt":"2024-11-03T13:01:16","guid":{"rendered":"https:\/\/server.hk\/cnblog\/160189\/"},"modified":"2024-11-03T21:01:17","modified_gmt":"2024-11-03T13:01:17","slug":"oceanbase-%e6%95%99%e7%a8%8b%ef%bc%9aoceanbase-nvl","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/160189\/","title":{"rendered":"OceanBase \u6559\u7a0b\uff1aOceanBase NVL"},"content":{"rendered":"<h1 id=\"oceanbase-%e6%95%99%e7%a8%8b%ef%bc%9aoceanbase-nvl-SHxAhkYjJu\">OceanBase \u6559\u7a0b\uff1aOceanBase NVL<\/h1>\n<p>\u5728\u7576\u4eca\u7684\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0cOceanBase \u4f5c\u70ba\u4e00\u500b\u9ad8\u6027\u80fd\u7684\u5206\u4f48\u5f0f\u6578\u64da\u5eab\uff0c\u8d8a\u4f86\u8d8a\u53d7\u5230\u958b\u767c\u8005\u548c\u4f01\u696d\u7684\u9752\u775e\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e OceanBase \u4e2d\u7684 NVL \u51fd\u6578\uff0c\u5e6b\u52a9\u8b80\u8005\u7406\u89e3\u5176\u7528\u6cd5\u53ca\u61c9\u7528\u5834\u666f\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%af-nvl-%e5%87%bd%e6%95%b8%ef%bc%9f-SHxAhkYjJu\">\u4ec0\u9ebc\u662f NVL \u51fd\u6578\uff1f<\/h2>\n<p>NVL \u51fd\u6578\u662f\u4e00\u500b\u5e38\u7528\u7684 SQL \u51fd\u6578\uff0c\u4e3b\u8981\u7528\u65bc\u8655\u7406\u7a7a\u503c\uff08NULL\uff09\u3002\u5728 OceanBase \u4e2d\uff0cNVL \u51fd\u6578\u7684\u4f5c\u7528\u662f\u5c07 NULL \u503c\u8f49\u63db\u70ba\u6307\u5b9a\u7684\u66ff\u4ee3\u503c\u3002\u9019\u5728\u6578\u64da\u67e5\u8a62\u548c\u5831\u544a\u4e2d\u975e\u5e38\u6709\u7528\uff0c\u56e0\u70ba NULL \u503c\u53ef\u80fd\u6703\u5c0e\u81f4\u8a08\u7b97\u932f\u8aa4\u6216\u4e0d\u5b8c\u6574\u7684\u7d50\u679c\u3002<\/p>\n<h2 id=\"nvl-%e5%87%bd%e6%95%b8%e7%9a%84%e8%aa%9e%e6%b3%95-SHxAhkYjJu\">NVL \u51fd\u6578\u7684\u8a9e\u6cd5<\/h2>\n<pre><code>NVL(expr1, expr2)<\/code><\/pre>\n<p>\u5728\u9019\u88e1\uff0c<code>expr1<\/code> \u662f\u8981\u6aa2\u67e5\u7684\u8868\u9054\u5f0f\uff0c\u5982\u679c <code>expr1<\/code> \u7684\u503c\u70ba NULL\uff0c\u5247\u8fd4\u56de <code>expr2<\/code> \u7684\u503c\uff1b\u5426\u5247\u8fd4\u56de <code>expr1<\/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-SHxAhkYjJu\">NVL \u51fd\u6578\u7684\u4f7f\u7528\u7bc4\u4f8b<\/h2>\n<p>\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528 NVL \u51fd\u6578\u7684\u7c21\u55ae\u7bc4\u4f8b\uff1a<\/p>\n<pre><code>SELECT NVL(column_name, '\u66ff\u4ee3\u503c') AS result\nFROM table_name;<\/code><\/pre>\n<p>\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u5982\u679c <code>column_name<\/code> \u7684\u503c\u70ba NULL\uff0c\u5247\u7d50\u679c\u5c07\u986f\u793a\u70ba &#8216;\u66ff\u4ee3\u503c&#8217;\u3002\u9019\u6a23\u53ef\u4ee5\u78ba\u4fdd\u67e5\u8a62\u7d50\u679c\u4e0d\u6703\u56e0\u70ba NULL \u503c\u800c\u51fa\u73fe\u7a7a\u767d\u3002<\/p>\n<h3 id=\"%e5%af%a6%e9%9a%9b%e6%87%89%e7%94%a8%e5%a0%b4%e6%99%af-SHxAhkYjJu\">\u5be6\u969b\u61c9\u7528\u5834\u666f<\/h3>\n<ul>\n<li><strong>\u5831\u544a\u751f\u6210\uff1a<\/strong>\u5728\u751f\u6210\u5831\u544a\u6642\uff0c\u4f7f\u7528 NVL \u51fd\u6578\u53ef\u4ee5\u78ba\u4fdd\u6240\u6709\u5b57\u6bb5\u90fd\u6709\u503c\uff0c\u5f9e\u800c\u63d0\u9ad8\u5831\u544a\u7684\u53ef\u8b80\u6027\u3002<\/li>\n<li><strong>\u6578\u64da\u6e05\u7406\uff1a<\/strong>\u5728\u6578\u64da\u6e05\u7406\u904e\u7a0b\u4e2d\uff0cNVL \u51fd\u6578\u53ef\u4ee5\u5e6b\u52a9\u958b\u767c\u8005\u5feb\u901f\u8b58\u5225\u548c\u66ff\u63db NULL \u503c\u3002<\/li>\n<li><strong>\u8a08\u7b97\u516c\u5f0f\uff1a<\/strong>\u5728\u8a08\u7b97\u516c\u5f0f\u4e2d\uff0c\u4f7f\u7528 NVL \u51fd\u6578\u53ef\u4ee5\u907f\u514d\u56e0 NULL \u503c\u5c0e\u81f4\u7684\u8a08\u7b97\u932f\u8aa4\u3002<\/li>\n<\/ul>\n<h2 id=\"%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-SHxAhkYjJu\">\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5728\u4f7f\u7528 NVL \u51fd\u6578\u6642\uff0c\u6709\u5e7e\u9ede\u9700\u8981\u6ce8\u610f\uff1a<\/p>\n<ul>\n<li>NVL \u51fd\u6578\u7684\u8fd4\u56de\u985e\u578b\u53d6\u6c7a\u65bc <code>expr1<\/code> \u548c <code>expr2<\/code> \u7684\u985e\u578b\u3002\u5982\u679c\u5169\u8005\u985e\u578b\u4e0d\u4e00\u81f4\uff0c\u53ef\u80fd\u6703\u5c0e\u81f4\u985e\u578b\u8f49\u63db\u932f\u8aa4\u3002<\/li>\n<li>\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c\u4f7f\u7528 COALESCE \u51fd\u6578\u53ef\u80fd\u66f4\u70ba\u5408\u9069\uff0c\u56e0\u70ba COALESCE \u53ef\u4ee5\u63a5\u53d7\u591a\u500b\u53c3\u6578\u4e26\u8fd4\u56de\u7b2c\u4e00\u500b\u975e NULL \u7684\u503c\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b5%90%e8%ab%96-SHxAhkYjJu\">\u7d50\u8ad6<\/h2>\n<p>NVL \u51fd\u6578\u5728 OceanBase \u4e2d\u662f\u4e00\u500b\u5f37\u5927\u7684\u5de5\u5177\uff0c\u80fd\u5920\u6709\u6548\u5730\u8655\u7406 NULL \u503c\uff0c\u5f9e\u800c\u63d0\u9ad8\u6578\u64da\u67e5\u8a62\u7684\u6e96\u78ba\u6027\u548c\u5b8c\u6574\u6027\u3002\u7121\u8ad6\u662f\u5728\u5831\u544a\u751f\u6210\u3001\u6578\u64da\u6e05\u7406\u9084\u662f\u8a08\u7b97\u516c\u5f0f\u4e2d\uff0c\u5408\u7406\u4f7f\u7528 NVL \u51fd\u6578\u90fd\u80fd\u5e36\u4f86\u986f\u8457\u7684\u597d\u8655\u3002<\/p>\n<p>\u5982\u679c\u60a8\u5c0d OceanBase \u6216\u5176\u4ed6\u6578\u64da\u5eab\u6280\u8853\u6709\u8208\u8da3\uff0c\u4e26\u5e0c\u671b\u7372\u5f97\u66f4\u9ad8\u6548\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0c\u8acb\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4ee5\u7372\u53d6\u66f4\u591a\u4fe1\u606f\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5b66\u4e60\u5982\u4f55\u4f7f\u7528 OceanBase NVL \u51fd\u6570\uff0c\u5904\u7406\u7a7a\u503c\u5e76\u4f18\u5316\u6570\u636e\u67e5\u8be2\uff0c\u63d0\u5347\u6570\u636e\u5e93\u64cd\u4f5c\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-160189","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160189","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=160189"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160189\/revisions"}],"predecessor-version":[{"id":160190,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/160189\/revisions\/160190"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=160189"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=160189"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=160189"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}