{"id":200002,"date":"2025-05-06T11:39:39","date_gmt":"2025-05-06T03:39:39","guid":{"rendered":"https:\/\/server.hk\/cnblog\/200002\/"},"modified":"2025-05-06T11:39:39","modified_gmt":"2025-05-06T03:39:39","slug":"%e6%b7%b1%e5%85%a5%e6%8e%a2%e8%ae%a8oracle%e4%b8%adnvl%e5%87%bd%e6%95%b0%e7%9a%84%e7%94%a8%e6%b3%95%e5%92%8c%e5%ae%9e%e9%99%85%e5%ba%94%e7%94%a8","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/200002\/","title":{"rendered":"\u6df1\u5165\u63a2\u8ba8Oracle\u4e2dNVL\u51fd\u6570\u7684\u7528\u6cd5\u548c\u5b9e\u9645\u5e94\u7528"},"content":{"rendered":"

<\/b> <\/p>\n

\u6df1\u5165\u63a2\u8ba8Oracle\u4e2dNVL\u51fd\u6570\u7684\u7528\u6cd5\u548c\u5b9e\u9645\u5e94\u7528<\/h1>\n

\u54c8\u55bd\uff01\u4eca\u5929\u5fc3\u8840\u6765\u6f6e\u7ed9\u5927\u5bb6\u5e26\u6765\u4e86\uff0c\u60f3\u5fc5\u5927\u5bb6\u5e94\u8be5\u5bf9\u90fd\u4e0d\u964c\u751f\u5427\uff0c\u90a3\u4e48\u9605\u8bfb\u672c\u6587\u5c31\u90fd\u4e0d\u4f1a\u5f88\u56f0\u96be\uff0c\u4ee5\u4e0b\u5185\u5bb9\u4e3b\u8981\u6d89\u53ca\u5230\uff0c\u82e5\u662f\u4f60\u6b63\u5728\u5b66\u4e60\uff0c\u5343\u4e07\u522b\u9519\u8fc7\u8fd9\u7bc7\u6587\u7ae0~\u5e0c\u671b\u80fd\u5e2e\u52a9\u5230\u4f60\uff01<\/p>\n

Oracle\u4e2d\u7684NVL\u51fd\u6570\u662f\u4e00\u79cd\u5904\u7406\u7a7a\u503c\uff08NULL\uff09\u7684\u51fd\u6570\uff0c\u5b83\u53ef\u4ee5\u7528\u4e8e\u66ff\u6362NULL\u503c\u4e3a\u6307\u5b9a\u7684\u503c\u3002\u5728\u672c\u6587\u4e2d\uff0c\u6211\u4eec\u5c06\u6df1\u5165\u63a2\u7a76NVL\u51fd\u6570\u7684\u4f7f\u7528\u65b9\u6cd5\u53ca\u5176\u5728\u4e0d\u540c\u573a\u666f\u4e0b\u7684\u5e94\u7528\u3002<\/p>\n

\u4e00\u3001NVL\u51fd\u6570\u89e3\u6790<\/h3>\n

NVL\u51fd\u6570\u7684\u8bed\u6cd5\u4e3a\uff1a<\/p>\n

NVL(expr1, expr2)<\/pre>\n
\u5176\u4e2d\uff0cexpr1\u662f\u9700\u8981\u5224\u65ad\u7684\u8868\u8fbe\u5f0f\uff0c\u5982\u679cexpr1\u4e3aNULL\uff0c\u5219\u8fd4\u56deexpr2\uff1b\u5982\u679cexpr1\u4e0d\u4e3aNULL\uff0c\u5219\u8fd4\u56deexpr1\u3002<\/p>\n
\u4e8c\u3001NVL\u51fd\u6570\u7684\u5e94\u7528\u573a\u666f<\/h3>\n
1. \u66ff\u6362\u67e5\u8be2\u7ed3\u679c\u4e2d\u7684NULL\u503c<\/h4>\n
\u5728\u6570\u636e\u5e93\u67e5\u8be2\u4e2d\uff0c\u5f80\u5f80\u4f1a\u51fa\u73b0\u67d0\u4e9b\u5b57\u6bb5\u7684\u503c\u4e3aNULL\u7684\u60c5\u51b5\uff0c\u8fd9\u65f6\u53ef\u4ee5\u4f7f\u7528NVL\u51fd\u6570\u5c06NULL\u503c\u66ff\u6362\u4e3a\u6307\u5b9a\u7684\u9ed8\u8ba4\u503c\u3002\u4ee5\u4e0b\u662f\u4e00\u4e2a\u7b80\u5355\u7684\u793a\u4f8b\uff1a<\/p>\n
SELECT column1, NVL(column2, '\u6682\u65e0\u6570\u636e') AS new_column\nFROM table_name;<\/pre>\n
\u4e0a\u8ff0\u4ee3\u7801\u4e2d\uff0c\u5982\u679ccolumn2\u7684\u503c\u4e3aNULL\uff0c\u67e5\u8be2\u7ed3\u679c\u4e2d\u5bf9\u5e94\u7684new_column\u5c06\u663e\u793a\u4e3a”\u6682\u65e0\u6570\u636e”\u3002<\/p>\n
2. \u6570\u636e\u5408\u5e76<\/h4>\n
\u5728\u6570\u636e\u5904\u7406\u8fc7\u7a0b\u4e2d\uff0c\u53ef\u80fd\u4f1a\u6d89\u53ca\u5230\u591a\u4e2a\u5b57\u6bb5\u7684\u5408\u5e76\u64cd\u4f5c\u3002NVL\u51fd\u6570\u53ef\u4ee5\u5e2e\u52a9\u6211\u4eec\u5728\u5408\u5e76\u8fc7\u7a0b\u4e2d\u5904\u7406NULL\u503c\uff0c\u786e\u4fdd\u6570\u636e\u7684\u5b8c\u6574\u6027\u3002\u4f8b\u5982\uff1a<\/p>\n
SELECT NVL(first_name, '\u672a\u77e5') || ' ' || NVL(last_name, '\u672a\u77e5') AS full_name\nFROM employee_table;<\/pre>\n
\u8fd9\u6bb5\u4ee3\u7801\u5c06\u5408\u5e76first_name\u548clast_name\u5b57\u6bb5\uff0c\u5e76\u5728\u5b57\u6bb5\u503c\u4e3aNULL\u65f6\u663e\u793a”\u672a\u77e5”\u3002<\/p>\n
3. \u6570\u503c\u5904\u7406<\/h4>\n
\u5bf9\u4e8e\u6570\u503c\u8ba1\u7b97\uff0cNVL\u51fd\u6570\u4e5f\u53ef\u4ee5\u6d3e\u4e0a\u7528\u573a\u3002\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7NVL\u51fd\u6570\u5c06NULL\u503c\u66ff\u6362\u4e3a0\uff0c\u4ee5\u907f\u514d\u5728\u8ba1\u7b97\u8fc7\u7a0b\u4e2d\u51fa\u73b0\u9519\u8bef\u3002\u4ee5\u4e0b\u662f\u4e00\u4e2a\u793a\u4f8b\uff1a<\/p>\n
SELECT NVL(salary, 0) AS adjusted_salary\nFROM employee_table;<\/pre>\n
\u4e09\u3001\u4ee3\u7801\u793a\u4f8b<\/h3>\n
\u4e3a\u4e86\u66f4\u52a0\u76f4\u89c2\u5730\u7406\u89e3NVL\u51fd\u6570\u7684\u4f7f\u7528\uff0c\u4ee5\u4e0b\u662f\u4e00\u4e2a\u5b8c\u6574\u7684\u4ee3\u7801\u793a\u4f8b\uff1a<\/p>\n
-- \u521b\u5efa\u4e00\u4e2a\u5305\u542bNULL\u503c\u7684\u6d4b\u8bd5\u8868\nCREATE TABLE test_table (\n    id NUMBER,\n    name VARCHAR2(50)\n);\n\nINSERT INTO test_table (id, name) VALUES (1, 'Alice');\nINSERT INTO test_table (id, name) VALUES (2, NULL);\nINSERT INTO test_table (id, name) VALUES (3, 'Bob');\nINSERT INTO test_table (id, name) VALUES (4, NULL);\n\n-- \u4f7f\u7528NVL\u51fd\u6570\u67e5\u8be2\u6570\u636e\nSELECT id, NVL(name, '\u672a\u77e5') AS updated_name\nFROM test_table;<\/pre>\n
\u56db\u3001\u603b\u7ed3<\/h3>\n
\u901a\u8fc7\u672c\u6587\u5bf9Oracle NVL\u51fd\u6570\u7684\u89e3\u6790\u4e0e\u5e94\u7528\u573a\u666f\u63a2\u7a76\uff0c\u6211\u4eec\u4e86\u89e3\u5230NVL\u51fd\u6570\u5728\u5904\u7406NULL\u503c\u65f6\u7684\u91cd\u8981\u4f5c\u7528\u3002\u65e0\u8bba\u662f\u66ff\u6362\u3001\u5408\u5e76\u8fd8\u662f\u6570\u503c\u5904\u7406\uff0cNVL\u51fd\u6570\u90fd\u80fd\u5e2e\u52a9\u6211\u4eec\u6709\u6548\u5730\u5904\u7406\u6570\u636e\uff0c\u4fdd\u8bc1\u67e5\u8be2\u7ed3\u679c\u7684\u51c6\u786e\u6027\u548c\u5b8c\u6574\u6027\u3002\u5728\u5b9e\u9645\u5f00\u53d1\u4e2d\uff0c\u719f\u7ec3\u8fd0\u7528NVL\u51fd\u6570\u5c06\u5927\u5927\u63d0\u5347\u6570\u636e\u5904\u7406\u7684\u6548\u7387\u4e0e\u51c6\u786e\u6027\u3002<\/p>\n
\u6587\u4e2d\u5173\u4e8eOracle,\u51fd\u6570,NVL\u7684\u77e5\u8bc6\u4ecb\u7ecd\uff0c\u5e0c\u671b\u5bf9\u4f60\u7684\u5b66\u4e60\u6709\u6240\u5e2e\u52a9\uff01\u82e5\u662f\u53d7\u76ca\u532a\u6d45\uff0c\u90a3\u5c31\u52a8\u52a8\u9f20\u6807\u6536\u85cf\u8fd9\u7bc7\u300a\u6df1\u5165\u63a2\u8ba8Oracle\u4e2dNVL\u51fd\u6570\u7684\u7528\u6cd5\u548c\u5b9e\u9645\u5e94\u7528\u300b\u6587\u7ae0\u5427\uff0c\u4e5f\u53ef\u5173\u6ce8\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\u4e86\u89e3\u76f8\u5173\u6280\u672f\u6587\u7ae0\u3002<\/p>\n
\n
\n <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"
\u6df1\u5165\u63a2\u8ba8Oracle\u4e2dNVL\u51fd\u6570...<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-200002","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200002","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"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=200002"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200002\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=200002"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=200002"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=200002"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}