{"id":178616,"date":"2024-11-08T19:27:19","date_gmt":"2024-11-08T11:27:19","guid":{"rendered":"https:\/\/server.hk\/cnblog\/178616\/"},"modified":"2024-11-08T19:27:20","modified_gmt":"2024-11-08T11:27:20","slug":"%e5%a6%82%e4%bd%95%e4%bf%ae%e5%be%a9postgresql%e9%8c%af%e8%aa%a4%e4%bb%a3%e7%a2%bc%ef%bc%9a01003-null_value_eliminated_in_set_function%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/178616\/","title":{"rendered":"\u5982\u4f55\u4fee\u5fa9PostgreSQL\u932f\u8aa4\u4ee3\u78bc\uff1a01003 – null_value_eliminated_in_set_function\uff1f"},"content":{"rendered":"

\u5982\u4f55\u4fee\u5fa9PostgreSQL\u932f\u8aa4\u4ee3\u78bc\uff1a01003 – null_value_eliminated_in_set_function\uff1f<\/h1>\n

\u5728\u4f7f\u7528PostgreSQL\u9032\u884c\u6578\u64da\u5eab\u64cd\u4f5c\u6642\uff0c\u958b\u767c\u8005\u53ef\u80fd\u6703\u9047\u5230\u5404\u7a2e\u932f\u8aa4\u4ee3\u78bc\uff0c\u5176\u4e2d\u4e4b\u4e00\u5c31\u662f\u932f\u8aa4\u4ee3\u78bc01003\uff0c\u8a72\u932f\u8aa4\u7684\u5b8c\u6574\u63cf\u8ff0\u70ba\u201cnull_value_eliminated_in_set_function\u201d\u3002\u9019\u500b\u932f\u8aa4\u901a\u5e38\u51fa\u73fe\u5728\u4f7f\u7528\u805a\u5408\u51fd\u6578\u6642\uff0c\u7576\u67d0\u4e9b\u884c\u7684\u503c\u70baNULL\u6642\uff0cPostgreSQL\u6703\u81ea\u52d5\u5ffd\u7565\u9019\u4e9bNULL\u503c\uff0c\u9019\u53ef\u80fd\u6703\u5c0e\u81f4\u610f\u5916\u7684\u7d50\u679c\u6216\u932f\u8aa4\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e\u9019\u500b\u932f\u8aa4\u7684\u539f\u56e0\u53ca\u5176\u89e3\u6c7a\u65b9\u6848\u3002<\/p>\n

\u932f\u8aa4\u539f\u56e0\u5206\u6790<\/h2>\n

\u7576\u4f60\u5728SQL\u67e5\u8a62\u4e2d\u4f7f\u7528\u805a\u5408\u51fd\u6578\uff08\u5982SUM\u3001AVG\u3001COUNT\u7b49\uff09\u6642\uff0c\u5982\u679c\u67d0\u4e9b\u884c\u7684\u503c\u70baNULL\uff0cPostgreSQL\u6703\u81ea\u52d5\u6392\u9664\u9019\u4e9bNULL\u503c\u3002\u9019\u6a23\u7684\u884c\u70ba\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\u662f\u5408\u7406\u7684\uff0c\u4f46\u5728\u5176\u4ed6\u60c5\u6cc1\u4e0b\uff0c\u958b\u767c\u8005\u53ef\u80fd\u5e0c\u671b\u80fd\u5920\u660e\u78ba\u5730\u8655\u7406\u9019\u4e9bNULL\u503c\u3002\u7576PostgreSQL\u6aa2\u6e2c\u5230\u9019\u7a2e\u60c5\u6cc1\u6642\uff0c\u4fbf\u6703\u8fd4\u56de\u932f\u8aa4\u4ee3\u78bc01003\u3002<\/p>\n

\u4f8b\u5982\uff0c\u8003\u616e\u4ee5\u4e0bSQL\u67e5\u8a62\uff1a<\/p>\n

SELECT AVG(salary) FROM employees;<\/code><\/pre>\n
\u5982\u679c\u67d0\u4e9b\u54e1\u5de5\u7684\u85aa\u6c34\u70baNULL\uff0c\u5247\u9019\u4e9b\u884c\u5c07\u88ab\u6392\u9664\u5728\u8a08\u7b97\u4e4b\u5916\uff0c\u4e26\u4e14PostgreSQL\u6703\u8fd4\u56de\u932f\u8aa401003\u3002\u9019\u610f\u5473\u8457\u5728\u8a08\u7b97\u5e73\u5747\u503c\u6642\uff0cNULL\u503c\u88ab\u81ea\u52d5\u5ffd\u7565\uff0c\u53ef\u80fd\u6703\u5c0e\u81f4\u958b\u767c\u8005\u5c0d\u7d50\u679c\u7684\u8aa4\u89e3\u3002<\/p>\n
\u89e3\u6c7a\u65b9\u6848<\/h2>\n
\u8981\u4fee\u5fa9\u9019\u500b\u932f\u8aa4\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u63a1\u53d6\u5e7e\u7a2e\u65b9\u6cd5\u4f86\u8655\u7406NULL\u503c\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684\u89e3\u6c7a\u65b9\u6848\uff1a<\/p>\n
1. \u4f7f\u7528COALESCE\u51fd\u6578<\/h3>\n
COALESCE\u51fd\u6578\u53ef\u4ee5\u7528\u4f86\u66ff\u63dbNULL\u503c\u3002\u9019\u6a23\u53ef\u4ee5\u78ba\u4fdd\u5728\u8a08\u7b97\u805a\u5408\u51fd\u6578\u6642\u4e0d\u6703\u51fa\u73feNULL\u503c\u3002\u4f8b\u5982\uff1a<\/p>\n
SELECT AVG(COALESCE(salary, 0)) FROM employees;<\/code><\/pre>\n
\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u6240\u6709\u7684NULL\u85aa\u6c34\u5c07\u88ab\u66ff\u63db\u70ba0\uff0c\u9019\u6a23\u8a08\u7b97\u7684\u5e73\u5747\u503c\u5c07\u5305\u542b\u6240\u6709\u54e1\u5de5\uff0c\u5373\u4f7f\u67d0\u4e9b\u85aa\u6c34\u70baNULL\u3002<\/p>\n
2. \u4f7f\u7528CASE\u8a9e\u53e5<\/h3>\n
\u53e6\u4e00\u7a2e\u65b9\u6cd5\u662f\u4f7f\u7528CASE\u8a9e\u53e5\u4f86\u8655\u7406NULL\u503c\u3002\u9019\u6a23\u53ef\u4ee5\u6839\u64da\u7279\u5b9a\u689d\u4ef6\u4f86\u6c7a\u5b9a\u5982\u4f55\u8655\u7406NULL\u503c\u3002\u4f8b\u5982\uff1a<\/p>\n
SELECT AVG(CASE WHEN salary IS NULL THEN 0 ELSE salary END) FROM employees;<\/code><\/pre>\n
\u9019\u500b\u67e5\u8a62\u7684\u6548\u679c\u8207\u4f7f\u7528COALESCE\u51fd\u6578\u76f8\u4f3c\uff0c\u4f46\u63d0\u4f9b\u4e86\u66f4\u5927\u7684\u9748\u6d3b\u6027\uff0c\u56e0\u70ba\u4f60\u53ef\u4ee5\u6839\u64da\u4e0d\u540c\u7684\u689d\u4ef6\u4f86\u8655\u7406NULL\u503c\u3002<\/p>\n
3. \u6aa2\u67e5\u6578\u64da\u5b8c\u6574\u6027<\/h3>\n
\u9664\u4e86\u5728\u67e5\u8a62\u4e2d\u8655\u7406NULL\u503c\u5916\uff0c\u9084\u61c9\u8a72\u6aa2\u67e5\u6578\u64da\u7684\u5b8c\u6574\u6027\u3002\u78ba\u4fdd\u5728\u63d2\u5165\u6578\u64da\u6642\uff0c\u5c0d\u65bc\u4e0d\u61c9\u70baNULL\u7684\u5b57\u6bb5\u9032\u884c\u9069\u7576\u7684\u7d04\u675f\u3002\u4f8b\u5982\uff0c\u53ef\u4ee5\u5728\u8868\u4e2d\u8a2d\u7f6eNOT NULL\u7d04\u675f\uff0c\u4ee5\u9632\u6b62\u5c07NULL\u503c\u63d2\u5165\u5230\u95dc\u9375\u5b57\u6bb5\u4e2d\u3002<\/p>\n
CREATE TABLE employees (\n    id SERIAL PRIMARY KEY,\n    name VARCHAR(100),\n    salary NUMERIC NOT NULL\n);<\/code><\/pre>\n
\u7e3d\u7d50<\/h2>\n
PostgreSQL\u932f\u8aa4\u4ee3\u78bc01003 – null_value_eliminated_in_set_function\u901a\u5e38\u662f\u7531\u65bc\u5728\u4f7f\u7528\u805a\u5408\u51fd\u6578\u6642\u9047\u5230NULL\u503c\u6240\u5f15\u8d77\u7684\u3002\u901a\u904e\u4f7f\u7528COALESCE\u51fd\u6578\u3001CASE\u8a9e\u53e5\u4ee5\u53ca\u6aa2\u67e5\u6578\u64da\u5b8c\u6574\u6027\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u6709\u6548\u5730\u89e3\u6c7a\u9019\u500b\u554f\u984c\uff0c\u78ba\u4fdd\u67e5\u8a62\u7d50\u679c\u7684\u6e96\u78ba\u6027\u3002\u5c0d\u65bc\u9700\u8981\u7a69\u5b9a\u548c\u9ad8\u6548\u6578\u64da\u5eab\u89e3\u6c7a\u65b9\u6848\u7684\u7528\u6236\uff0c\u9078\u64c7\u5408\u9069\u7684\u9999\u6e2fVPS<\/a><\/code>\u6216\u4e91\u670d\u52a1\u5668<\/a><\/code>\u53ef\u4ee5\u63d0\u4f9b\u66f4\u597d\u7684\u6027\u80fd\u548c\u53ef\u9760\u6027\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u4e86\u89e3\u5982\u4f55\u4fee\u5fa9PostgreSQL\u932f\u8aa4\u4ee3\u78bc01003\uff0c\u89e3\u6c7a\u5728\u96c6\u5408\u51fd\u6578\u4e2d\u6d88\u9664\u7a7a\u503c\u7684\u554f\u984c\uff0c\u63d0\u5347\u6578\u64da\u67e5\u8a62\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-178616","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/178616","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=178616"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/178616\/revisions"}],"predecessor-version":[{"id":178617,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/178616\/revisions\/178617"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=178616"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=178616"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=178616"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}