{"id":178672,"date":"2024-11-08T19:55:17","date_gmt":"2024-11-08T11:55:17","guid":{"rendered":"https:\/\/server.hk\/cnblog\/178672\/"},"modified":"2024-11-08T19:55:18","modified_gmt":"2024-11-08T11:55:18","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%9a21000-cardinality_violation%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/178672\/","title":{"rendered":"\u5982\u4f55\u4fee\u5fa9PostgreSQL\u932f\u8aa4\u4ee3\u78bc\uff1a21000 &#8211; cardinality_violation\uff1f"},"content":{"rendered":"<h1 id=\"%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%9a21000-cardinality_violation-TQIdMFueWS\">\u5982\u4f55\u4fee\u5fa9PostgreSQL\u932f\u8aa4\u4ee3\u78bc\uff1a21000 &#8211; cardinality_violation<\/h1>\n<p>\u5728\u4f7f\u7528PostgreSQL\u6578\u64da\u5eab\u6642\uff0c\u958b\u767c\u8005\u53ef\u80fd\u6703\u9047\u5230\u5404\u7a2e\u932f\u8aa4\u4ee3\u78bc\uff0c\u5176\u4e2d\u4e4b\u4e00\u5c31\u662f21000 &#8211; cardinality_violation\u3002\u9019\u500b\u932f\u8aa4\u901a\u5e38\u767c\u751f\u5728\u57f7\u884c\u67e5\u8a62\u6642\uff0c\u7576\u67e5\u8a62\u7684\u7d50\u679c\u96c6\u8207\u9810\u671f\u7684\u884c\u6578\u4e0d\u7b26\u6642\uff0c\u7279\u5225\u662f\u5728\u4f7f\u7528\u805a\u5408\u51fd\u6578\u6216\u5b50\u67e5\u8a62\u6642\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e\u9019\u500b\u932f\u8aa4\u7684\u539f\u56e0\u53ca\u5176\u89e3\u6c7a\u65b9\u6cd5\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%afcardinality_violation%ef%bc%9f-TQIdMFueWS\">\u4ec0\u9ebc\u662fcardinality_violation\uff1f<\/h2>\n<p>Cardinality violation\u6307\u7684\u662f\u5728\u67e5\u8a62\u4e2d\uff0c\u8fd4\u56de\u7684\u884c\u6578\u8207\u9810\u671f\u7684\u884c\u6578\u4e0d\u4e00\u81f4\u3002\u9019\u901a\u5e38\u767c\u751f\u5728\u4ee5\u4e0b\u60c5\u6cc1\uff1a<\/p>\n<ul>\n<li>\u4f7f\u7528\u4e86\u805a\u5408\u51fd\u6578\uff08\u5982SUM\u3001COUNT\u7b49\uff09\u4f46\u672a\u6b63\u78ba\u4f7f\u7528GROUP BY\u5b50\u53e5\u3002<\/li>\n<li>\u5728\u5b50\u67e5\u8a62\u4e2d\u8fd4\u56de\u591a\u65bc\u4e00\u884c\u7684\u7d50\u679c\uff0c\u800c\u5916\u90e8\u67e5\u8a62\u671f\u671b\u53ea\u6709\u4e00\u884c\u3002<\/li>\n<li>\u5728JOIN\u64cd\u4f5c\u4e2d\uff0c\u672a\u6b63\u78ba\u8655\u7406\u591a\u5c0d\u591a\u7684\u95dc\u4fc2\u3002<\/li>\n<\/ul>\n<h2 id=\"%e5%b8%b8%e8%a6%8b%e5%a0%b4%e6%99%af%e5%8f%8a%e7%a4%ba%e4%be%8b-TQIdMFueWS\">\u5e38\u898b\u5834\u666f\u53ca\u793a\u4f8b<\/h2>\n<h3 id=\"1-%e8%81%9a%e5%90%88%e5%87%bd%e6%95%b8%e8%88%87group-by-TQIdMFueWS\">1. \u805a\u5408\u51fd\u6578\u8207GROUP BY<\/h3>\n<p>\u7576\u4f7f\u7528\u805a\u5408\u51fd\u6578\u6642\uff0c\u5fc5\u9808\u78ba\u4fdd\u4f7f\u7528GROUP BY\u5b50\u53e5\u4f86\u6b63\u78ba\u5206\u7d44\u6578\u64da\u3002\u4f8b\u5982\uff0c\u4ee5\u4e0b\u67e5\u8a62\u5c07\u5c0e\u81f4cardinality_violation\u932f\u8aa4\uff1a<\/p>\n<pre><code>SELECT department, COUNT(*) FROM employees;<\/code><\/pre>\n<p>\u56e0\u70ba\u6c92\u6709GROUP BY\u5b50\u53e5\uff0cPostgreSQL\u7121\u6cd5\u78ba\u5b9a\u5982\u4f55\u5c0d\u7d50\u679c\u9032\u884c\u5206\u7d44\u3002\u6b63\u78ba\u7684\u67e5\u8a62\u61c9\u8a72\u662f\uff1a<\/p>\n<pre><code>SELECT department, COUNT(*) FROM employees GROUP BY department;<\/code><\/pre>\n<h3 id=\"2-%e5%ad%90%e6%9f%a5%e8%a9%a2%e8%bf%94%e5%9b%9e%e5%a4%9a%e8%a1%8c-TQIdMFueWS\">2. \u5b50\u67e5\u8a62\u8fd4\u56de\u591a\u884c<\/h3>\n<p>\u5982\u679c\u5728WHERE\u5b50\u53e5\u4e2d\u4f7f\u7528\u4e86\u5b50\u67e5\u8a62\uff0c\u4e26\u4e14\u8a72\u5b50\u67e5\u8a62\u8fd4\u56de\u591a\u65bc\u4e00\u884c\u7684\u7d50\u679c\uff0c\u5247\u6703\u5f15\u767ccardinality_violation\u932f\u8aa4\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>SELECT * FROM employees WHERE department_id = (SELECT id FROM departments);<\/code><\/pre>\n<p>\u5982\u679cdepartments\u8868\u4e2d\u6709\u591a\u65bc\u4e00\u884c\uff0c\u9019\u5c07\u5c0e\u81f4\u932f\u8aa4\u3002\u53ef\u4ee5\u4f7f\u7528IN\u4f86\u89e3\u6c7a\u9019\u500b\u554f\u984c\uff1a<\/p>\n<pre><code>SELECT * FROM employees WHERE department_id IN (SELECT id FROM departments);<\/code><\/pre>\n<h3 id=\"3-join%e6%93%8d%e4%bd%9c%e4%b8%ad%e7%9a%84%e5%a4%9a%e5%b0%8d%e5%a4%9a%e9%97%9c%e4%bf%82-TQIdMFueWS\">3. JOIN\u64cd\u4f5c\u4e2d\u7684\u591a\u5c0d\u591a\u95dc\u4fc2<\/h3>\n<p>\u5728\u9032\u884cJOIN\u64cd\u4f5c\u6642\uff0c\u82e5\u672a\u6b63\u78ba\u8655\u7406\u591a\u5c0d\u591a\u7684\u95dc\u4fc2\uff0c\u4e5f\u53ef\u80fd\u5c0e\u81f4cardinality_violation\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>SELECT a.*, b.* FROM table_a a JOIN table_b b ON a.id = b.a_id WHERE a.some_column = 'value';<\/code><\/pre>\n<p>\u5982\u679ctable_a\u548ctable_b\u4e4b\u9593\u5b58\u5728\u591a\u5c0d\u591a\u7684\u95dc\u4fc2\uff0c\u5247\u53ef\u80fd\u6703\u8fd4\u56de\u610f\u5916\u7684\u884c\u6578\u3002\u70ba\u4e86\u907f\u514d\u9019\u7a2e\u60c5\u6cc1\uff0c\u61c9\u8a72\u4ed4\u7d30\u8a2d\u8a08\u6578\u64da\u6a21\u578b\uff0c\u4e26\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528\u9069\u7576\u7684\u689d\u4ef6\u4f86\u9650\u5236\u7d50\u679c\u96c6\u3002<\/p>\n<h2 id=\"%e5%a6%82%e4%bd%95%e4%bf%ae%e5%be%a9cardinality_violation%e9%8c%af%e8%aa%a4-TQIdMFueWS\">\u5982\u4f55\u4fee\u5fa9cardinality_violation\u932f\u8aa4<\/h2>\n<p>\u4fee\u5fa9cardinality_violation\u932f\u8aa4\u7684\u95dc\u9375\u5728\u65bc\u4ed4\u7d30\u6aa2\u67e5\u67e5\u8a62\u7684\u908f\u8f2f\u548c\u7d50\u69cb\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5efa\u8b70\uff1a<\/p>\n<ul>\n<li>\u6aa2\u67e5\u6240\u6709\u805a\u5408\u51fd\u6578\uff0c\u78ba\u4fdd\u6b63\u78ba\u4f7f\u7528GROUP BY\u5b50\u53e5\u3002<\/li>\n<li>\u5728\u4f7f\u7528\u5b50\u67e5\u8a62\u6642\uff0c\u78ba\u4fdd\u5176\u8fd4\u56de\u7684\u884c\u6578\u7b26\u5408\u5916\u90e8\u67e5\u8a62\u7684\u9810\u671f\u3002<\/li>\n<li>\u5728JOIN\u64cd\u4f5c\u4e2d\uff0c\u8003\u616e\u6578\u64da\u6a21\u578b\u7684\u8a2d\u8a08\uff0c\u907f\u514d\u4e0d\u5fc5\u8981\u7684\u591a\u5c0d\u591a\u95dc\u4fc2\u3002<\/li>\n<li>\u4f7f\u7528LIMIT\u5b50\u53e5\u4f86\u9650\u5236\u67e5\u8a62\u7d50\u679c\u7684\u884c\u6578\uff0c\u7279\u5225\u662f\u5728\u4e0d\u78ba\u5b9a\u8fd4\u56de\u884c\u6578\u7684\u60c5\u6cc1\u4e0b\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-TQIdMFueWS\">\u7e3d\u7d50<\/h2>\n<p>PostgreSQL\u768421000 &#8211; cardinality_violation\u932f\u8aa4\u901a\u5e38\u662f\u7531\u65bc\u67e5\u8a62\u7d50\u69cb\u4e0d\u7576\u6216\u6578\u64da\u6a21\u578b\u8a2d\u8a08\u4e0d\u826f\u6240\u5f15\u8d77\u7684\u3002\u901a\u904e\u4ed4\u7d30\u6aa2\u67e5\u67e5\u8a62\u908f\u8f2f\u3001\u4f7f\u7528\u6b63\u78ba\u7684\u805a\u5408\u51fd\u6578\u548c\u5b50\u67e5\u8a62\uff0c\u4ee5\u53ca\u5408\u7406\u8a2d\u8a08\u6578\u64da\u6a21\u578b\uff0c\u53ef\u4ee5\u6709\u6548\u5730\u907f\u514d\u9019\u985e\u932f\u8aa4\u7684\u767c\u751f\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u6578\u64da\u8655\u7406\u7684\u61c9\u7528\uff0c\u9078\u64c7\u5408\u9069\u7684<a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a>\u6216<a href=\"https:\/\/server.hk\">\u96f2\u4f3a\u670d\u5668<\/a>\u89e3\u6c7a\u65b9\u6848\u4e5f\u662f\u81f3\u95dc\u91cd\u8981\u7684\uff0c\u4ee5\u78ba\u4fdd\u6578\u64da\u5eab\u7684\u7a69\u5b9a\u6027\u548c\u6027\u80fd\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3\u5982\u4f55\u4fee\u5fa9PostgreSQL\u932f\u8aa4\u4ee3\u78bc21000 &#8211; cardinality_violation\uff0c\u89e3\u6c7a\u67e5\u8a62\u4e2d\u7684\u6578\u64da\u4e0d\u4e00\u81f4\u554f\u984c\uff0c\u78ba\u4fdd\u6578\u64da\u5b8c\u6574\u6027\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-178672","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/178672","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=178672"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/178672\/revisions"}],"predecessor-version":[{"id":178673,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/178672\/revisions\/178673"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=178672"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=178672"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=178672"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}