{"id":179036,"date":"2024-11-08T22:28:23","date_gmt":"2024-11-08T14:28:23","guid":{"rendered":"https:\/\/server.hk\/cnblog\/179036\/"},"modified":"2024-11-08T22:28:24","modified_gmt":"2024-11-08T14:28:24","slug":"%e5%a6%82%e4%bd%95%e4%bf%ae%e5%be%a9-postgresql-%e9%8c%af%e8%aa%a4%e4%bb%a3%e7%a2%bc%ef%bc%9a42p09-ambiguous_alias%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/179036\/","title":{"rendered":"\u5982\u4f55\u4fee\u5fa9 PostgreSQL \u932f\u8aa4\u4ee3\u78bc\uff1a42P09 &#8211; ambiguous_alias\uff1f"},"content":{"rendered":"<h1 id=\"%e5%a6%82%e4%bd%95%e4%bf%ae%e5%be%a9-postgresql-%e9%8c%af%e8%aa%a4%e4%bb%a3%e7%a2%bc%ef%bc%9a42p09-ambiguous_alias-ybnqQBwJlz\">\u5982\u4f55\u4fee\u5fa9 PostgreSQL \u932f\u8aa4\u4ee3\u78bc\uff1a42P09 &#8211; ambiguous_alias<\/h1>\n<p>\u5728\u4f7f\u7528 PostgreSQL \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\u662f\u932f\u8aa4\u4ee3\u78bc 42P09\uff0c\u8a72\u932f\u8aa4\u901a\u5e38\u8868\u793a\u300c\u6a21\u7cca\u7684\u5225\u540d\u300d\uff08ambiguous alias\uff09\u3002\u9019\u500b\u932f\u8aa4\u901a\u5e38\u767c\u751f\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528\u4e86\u91cd\u8907\u7684\u5225\u540d\uff0c\u6216\u8005\u5728\u4f7f\u7528 JOIN \u64cd\u4f5c\u6642\uff0c\u672a\u80fd\u6b63\u78ba\u5340\u5206\u4e0d\u540c\u8868\u4e2d\u7684\u5217\u540d\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u9019\u500b\u932f\u8aa4\u7684\u6210\u56e0\u53ca\u5176\u89e3\u6c7a\u65b9\u6cd5\u3002<\/p>\n<h2 id=\"%e9%8c%af%e8%aa%a4%e4%bb%a3%e7%a2%bc-42p09-%e7%9a%84%e6%88%90%e5%9b%a0-ybnqQBwJlz\">\u932f\u8aa4\u4ee3\u78bc 42P09 \u7684\u6210\u56e0<\/h2>\n<p>\u7576\u4f60\u5728 SQL \u67e5\u8a62\u4e2d\u4f7f\u7528\u4e86\u76f8\u540c\u7684\u5225\u540d\uff0c\u6216\u8005\u5728\u591a\u500b\u8868\u4e2d\u5b58\u5728\u540c\u540d\u7684\u5217\u6642\uff0cPostgreSQL \u6703\u7121\u6cd5\u78ba\u5b9a\u4f60\u6240\u6307\u7684\u5177\u9ad4\u5217\uff0c\u5f9e\u800c\u5f15\u767c 42P09 \u932f\u8aa4\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684\u60c5\u6cc1\uff1a<\/p>\n<ul>\n<li><strong>\u91cd\u8907\u7684\u5225\u540d\uff1a<\/strong>\u5728 SELECT \u8a9e\u53e5\u4e2d\u70ba\u4e0d\u540c\u7684\u5217\u4f7f\u7528\u4e86\u76f8\u540c\u7684\u5225\u540d\u3002<\/li>\n<li><strong>JOIN \u64cd\u4f5c\u4e2d\u7684\u5217\u540d\u885d\u7a81\uff1a<\/strong>\u5728\u591a\u500b\u8868\u4e2d\u5b58\u5728\u540c\u540d\u7684\u5217\uff0c\u4e14\u672a\u4f7f\u7528\u8868\u540d\u6216\u8868\u5225\u540d\u4f86\u660e\u78ba\u6307\u5b9a\u3002<\/li>\n<li><strong>\u5b50\u67e5\u8a62\u4e2d\u7684\u5225\u540d\u885d\u7a81\uff1a<\/strong>\u5728\u5b50\u67e5\u8a62\u4e2d\u4f7f\u7528\u4e86\u8207\u5916\u90e8\u67e5\u8a62\u76f8\u540c\u7684\u5225\u540d\u3002<\/li>\n<\/ul>\n<h2 id=\"%e5%a6%82%e4%bd%95%e4%bf%ae%e5%be%a9-42p09-%e9%8c%af%e8%aa%a4-ybnqQBwJlz\">\u5982\u4f55\u4fee\u5fa9 42P09 \u932f\u8aa4<\/h2>\n<p>\u8981\u4fee\u5fa9 PostgreSQL \u7684 42P09 \u932f\u8aa4\uff0c\u958b\u767c\u8005\u9700\u8981\u4ed4\u7d30\u6aa2\u67e5 SQL \u67e5\u8a62\uff0c\u78ba\u4fdd\u6240\u6709\u7684\u5225\u540d\u90fd\u662f\u552f\u4e00\u7684\uff0c\u4e26\u4e14\u5728\u9700\u8981\u7684\u5730\u65b9\u4f7f\u7528\u8868\u540d\u6216\u8868\u5225\u540d\u4f86\u660e\u78ba\u6307\u5b9a\u5217\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5177\u9ad4\u7684\u89e3\u6c7a\u65b9\u6848\uff1a<\/p>\n<h3 id=\"1-%e7%a2%ba%e4%bf%9d%e5%88%a5%e5%90%8d%e5%94%af%e4%b8%80-ybnqQBwJlz\">1. \u78ba\u4fdd\u5225\u540d\u552f\u4e00<\/h3>\n<p>\u5728 SELECT \u8a9e\u53e5\u4e2d\uff0c\u70ba\u6bcf\u500b\u5217\u6307\u5b9a\u552f\u4e00\u7684\u5225\u540d\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>SELECT \n    a.id AS user_id, \n    a.name AS user_name, \n    b.id AS order_id, \n    b.amount AS order_amount \nFROM \n    users a \nJOIN \n    orders b ON a.id = b.user_id;<\/code><\/pre>\n<h3 id=\"2-%e4%bd%bf%e7%94%a8%e8%a1%a8%e5%90%8d%e6%88%96%e8%a1%a8%e5%88%a5%e5%90%8d-ybnqQBwJlz\">2. \u4f7f\u7528\u8868\u540d\u6216\u8868\u5225\u540d<\/h3>\n<p>\u5728\u6d89\u53ca\u591a\u500b\u8868\u7684\u67e5\u8a62\u4e2d\uff0c\u4f7f\u7528\u8868\u540d\u6216\u8868\u5225\u540d\u4f86\u660e\u78ba\u6307\u5b9a\u5217\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>SELECT \n    users.id, \n    orders.amount \nFROM \n    users \nJOIN \n    orders ON users.id = orders.user_id;<\/code><\/pre>\n<h3 id=\"3-%e6%aa%a2%e6%9f%a5%e5%ad%90%e6%9f%a5%e8%a9%a2%e4%b8%ad%e7%9a%84%e5%88%a5%e5%90%8d-ybnqQBwJlz\">3. \u6aa2\u67e5\u5b50\u67e5\u8a62\u4e2d\u7684\u5225\u540d<\/h3>\n<p>\u5982\u679c\u4f7f\u7528\u4e86\u5b50\u67e5\u8a62\uff0c\u78ba\u4fdd\u5b50\u67e5\u8a62\u4e2d\u7684\u5225\u540d\u4e0d\u8207\u5916\u90e8\u67e5\u8a62\u4e2d\u7684\u5225\u540d\u885d\u7a81\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>SELECT \n    u.id, \n    (SELECT COUNT(*) FROM orders o WHERE o.user_id = u.id) AS order_count \nFROM \n    users u;<\/code><\/pre>\n<h2 id=\"%e7%a4%ba%e4%be%8b%e5%88%86%e6%9e%90-ybnqQBwJlz\">\u793a\u4f8b\u5206\u6790<\/h2>\n<p>\u8003\u616e\u4ee5\u4e0b\u67e5\u8a62\uff0c\u9019\u53ef\u80fd\u6703\u5c0e\u81f4 42P09 \u932f\u8aa4\uff1a<\/p>\n<pre><code>SELECT \n    id AS user_id, \n    id AS order_id \nFROM \n    users;<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u56e0\u70ba\u5169\u500b\u5217\u90fd\u4f7f\u7528\u4e86\u76f8\u540c\u7684\u5225\u540d\u300cid\u300d\uff0c\u6240\u4ee5 PostgreSQL \u7121\u6cd5\u78ba\u5b9a\u61c9\u8a72\u8fd4\u56de\u54ea\u4e00\u500b\u3002\u4fee\u6b63\u5f8c\u7684\u67e5\u8a62\u61c9\u8a72\u662f\uff1a<\/p>\n<pre><code>SELECT \n    id AS user_id, \n    order_id \nFROM \n    users;<\/code><\/pre>\n<h2 id=\"%e7%b8%bd%e7%b5%90-ybnqQBwJlz\">\u7e3d\u7d50<\/h2>\n<p>PostgreSQL \u932f\u8aa4\u4ee3\u78bc 42P09 \u901a\u5e38\u662f\u7531\u65bc\u6a21\u7cca\u7684\u5225\u540d\u6216\u5217\u540d\u885d\u7a81\u5f15\u8d77\u7684\u3002\u901a\u904e\u78ba\u4fdd\u6240\u6709\u5225\u540d\u7684\u552f\u4e00\u6027\uff0c\u4e26\u5728\u67e5\u8a62\u4e2d\u660e\u78ba\u6307\u5b9a\u8868\u540d\u6216\u8868\u5225\u540d\uff0c\u53ef\u4ee5\u6709\u6548\u5730\u907f\u514d\u9019\u500b\u932f\u8aa4\u3002\u9019\u4e0d\u50c5\u80fd\u63d0\u9ad8\u67e5\u8a62\u7684\u53ef\u8b80\u6027\uff0c\u9084\u80fd\u6e1b\u5c11\u6f5b\u5728\u7684\u932f\u8aa4\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u6eff\u8db3\u4e0d\u540c\u9700\u6c42\u7684\u7528\u6236\u3002\u7121\u8ad6\u662f\u6578\u64da\u5eab\u7ba1\u7406\u9084\u662f\u7db2\u7ad9\u6258\u7ba1\uff0c\u6211\u5011\u7684 <a href=\"https:\/\/server.hk\">\u4f3a\u670d\u5668<\/a> \u90fd\u80fd\u70ba\u60a8\u63d0\u4f9b\u7a69\u5b9a\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3\u5982\u4f55\u4fee\u5fa9 PostgreSQL \u932f\u8aa4\u4ee3\u78bc 42P09 &#8211; ambiguous_alias\uff0c\u89e3\u6c7a\u67e5\u8a62\u4e2d\u6a21\u7cca\u5225\u540d\u554f\u984c\uff0c\u63d0\u5347\u6578\u64da\u5eab\u6027\u80fd\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-179036","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/179036","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=179036"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/179036\/revisions"}],"predecessor-version":[{"id":179037,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/179036\/revisions\/179037"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=179036"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=179036"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=179036"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}