{"id":178780,"date":"2024-11-08T20:50:19","date_gmt":"2024-11-08T12:50:19","guid":{"rendered":"https:\/\/server.hk\/cnblog\/178780\/"},"modified":"2024-11-08T20:50:20","modified_gmt":"2024-11-08T12:50:20","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%9a22038-singleton_sql_json_item_required%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/178780\/","title":{"rendered":"\u5982\u4f55\u4fee\u5fa9PostgreSQL\u932f\u8aa4\u4ee3\u78bc\uff1a22038 &#8211; singleton_sql_json_item_required\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%9a22038-singleton_sql_json_item_required-ILosjsnzHX\">\u5982\u4f55\u4fee\u5fa9PostgreSQL\u932f\u8aa4\u4ee3\u78bc\uff1a22038 &#8211; singleton_sql_json_item_required<\/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\u662f\u932f\u8aa4\u4ee3\u78bc22038\uff0c\u8a72\u932f\u8aa4\u901a\u5e38\u8207JSON\u6578\u64da\u985e\u578b\u7684\u64cd\u4f5c\u6709\u95dc\u3002\u5177\u9ad4\u4f86\u8aaa\uff0c\u9019\u500b\u932f\u8aa4\u8868\u793a\u5728\u57f7\u884c\u67d0\u4e9b\u64cd\u4f5c\u6642\uff0c\u7cfb\u7d71\u671f\u671b\u4e00\u500b\u55ae\u4e00\u7684JSON\u9805\u76ee\uff0c\u4f46\u537b\u5f97\u5230\u4e86\u591a\u500b\u9805\u76ee\u6216\u7a7a\u503c\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u9019\u500b\u932f\u8aa4\u7684\u539f\u56e0\u53ca\u5176\u89e3\u6c7a\u65b9\u6848\u3002<\/p>\n<h2 id=\"%e9%8c%af%e8%aa%a4%e4%bb%a3%e7%a2%bc22038%e7%9a%84%e5%8e%9f%e5%9b%a0-ILosjsnzHX\">\u932f\u8aa4\u4ee3\u78bc22038\u7684\u539f\u56e0<\/h2>\n<p>PostgreSQL\u7684JSON\u548cJSONB\u6578\u64da\u985e\u578b\u5141\u8a31\u7528\u6236\u5b58\u5132\u548c\u67e5\u8a62\u7d50\u69cb\u5316\u6578\u64da\u3002\u7576\u4f60\u5617\u8a66\u5f9e\u4e00\u500bJSON\u6578\u7d44\u4e2d\u63d0\u53d6\u4e00\u500b\u9805\u76ee\u6642\uff0c\u5982\u679c\u8a72\u64cd\u4f5c\u671f\u671b\u4e00\u500b\u55ae\u4e00\u7684\u9805\u76ee\u800c\u4f60\u63d0\u4f9b\u4e86\u591a\u500b\u9805\u76ee\uff0c\u5247\u6703\u5f15\u767c22038\u932f\u8aa4\u3002\u9019\u901a\u5e38\u767c\u751f\u5728\u4ee5\u4e0b\u60c5\u6cc1\uff1a<\/p>\n<ul>\n<li>\u4f7f\u7528\u4e86\u4e0d\u6b63\u78ba\u7684JSON\u51fd\u6578\uff0c\u4f8b\u5982 <code>json_array_elements()<\/code>\uff0c\u800c\u671f\u671b\u7684\u537b\u662f\u55ae\u4e00\u7684JSON\u5c0d\u8c61\u3002<\/li>\n<li>\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528\u4e86\u4e0d\u6b63\u78ba\u7684\u8def\u5f91\uff0c\u5c0e\u81f4\u8fd4\u56de\u4e86\u591a\u500b\u503c\u3002<\/li>\n<li>\u6578\u64da\u672c\u8eab\u7684\u7d50\u69cb\u4e0d\u7b26\u5408\u9810\u671f\uff0c\u4f8b\u5982\uff0c\u61c9\u8a72\u662f\u55ae\u4e00\u5c0d\u8c61\u7684\u5730\u65b9\u537b\u662f\u4e00\u500b\u6578\u7d44\u3002<\/li>\n<\/ul>\n<h2 id=\"%e5%a6%82%e4%bd%95%e4%bf%ae%e5%be%a9%e9%8c%af%e8%aa%a4-ILosjsnzHX\">\u5982\u4f55\u4fee\u5fa9\u932f\u8aa4<\/h2>\n<p>\u8981\u4fee\u5fa922038\u932f\u8aa4\uff0c\u9996\u5148\u9700\u8981\u78ba\u5b9a\u5f15\u767c\u932f\u8aa4\u7684\u5177\u9ad4\u67e5\u8a62\u6216\u64cd\u4f5c\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684\u89e3\u6c7a\u65b9\u6848\uff1a<\/p>\n<h3 id=\"1-%e6%aa%a2%e6%9f%a5json%e7%b5%90%e6%a7%8b-ILosjsnzHX\">1. \u6aa2\u67e5JSON\u7d50\u69cb<\/h3>\n<p>\u9996\u5148\uff0c\u6aa2\u67e5\u4f60\u6b63\u5728\u64cd\u4f5c\u7684JSON\u6578\u64da\u7d50\u69cb\u3002\u78ba\u4fdd\u4f60\u671f\u671b\u7684\u6578\u64da\u683c\u5f0f\u8207\u5be6\u969b\u6578\u64da\u683c\u5f0f\u76f8\u7b26\u3002\u4f8b\u5982\uff0c\u5982\u679c\u4f60\u671f\u671b\u4e00\u500b\u55ae\u4e00\u7684JSON\u5c0d\u8c61\uff0c\u8acb\u78ba\u8a8d\u8a72\u5c0d\u8c61\u4e0d\u662f\u4e00\u500b\u6578\u7d44\u3002\u4f60\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u67e5\u8a62\u4f86\u6aa2\u67e5\u6578\u64da\uff1a<\/p>\n<pre><code>SELECT your_json_column FROM your_table WHERE your_conditions;<\/code><\/pre>\n<h3 id=\"2-%e4%bd%bf%e7%94%a8%e6%ad%a3%e7%a2%ba%e7%9a%84json%e5%87%bd%e6%95%b8-ILosjsnzHX\">2. \u4f7f\u7528\u6b63\u78ba\u7684JSON\u51fd\u6578<\/h3>\n<p>\u78ba\u4fdd\u4f7f\u7528\u6b63\u78ba\u7684JSON\u51fd\u6578\u4f86\u63d0\u53d6\u6578\u64da\u3002\u5982\u679c\u4f60\u9700\u8981\u5f9eJSON\u6578\u7d44\u4e2d\u63d0\u53d6\u55ae\u4e00\u9805\u76ee\uff0c\u53ef\u4ee5\u4f7f\u7528 <code>jsonb_array_elements()<\/code> \u51fd\u6578\uff0c\u7136\u5f8c\u4f7f\u7528 <code>LIMIT 1<\/code> \u4f86\u9650\u5236\u8fd4\u56de\u7684\u7d50\u679c\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>SELECT jsonb_array_elements(your_json_column) AS item\nFROM your_table\nWHERE your_conditions\nLIMIT 1;<\/code><\/pre>\n<h3 id=\"3-%e4%bd%bf%e7%94%a8case%e8%aa%9e%e5%8f%a5%e8%99%95%e7%90%86%e5%a4%9a%e5%80%8b%e9%a0%85%e7%9b%ae-ILosjsnzHX\">3. \u4f7f\u7528CASE\u8a9e\u53e5\u8655\u7406\u591a\u500b\u9805\u76ee<\/h3>\n<p>\u5982\u679c\u4f60\u7684\u67e5\u8a62\u53ef\u80fd\u8fd4\u56de\u591a\u500b\u9805\u76ee\uff0c\u53ef\u4ee5\u8003\u616e\u4f7f\u7528 <code>CASE<\/code> \u8a9e\u53e5\u4f86\u8655\u7406\u9019\u4e9b\u60c5\u6cc1\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>SELECT CASE\n    WHEN jsonb_typeof(your_json_column) = 'array' THEN (your_json_column-&gt;&gt;0)\n    ELSE your_json_column\nEND AS single_item\nFROM your_table\nWHERE your_conditions;<\/code><\/pre>\n<h2 id=\"%e7%a4%ba%e4%be%8b-ILosjsnzHX\">\u793a\u4f8b<\/h2>\n<p>\u5047\u8a2d\u4f60\u6709\u4e00\u500b\u8868\u683c <code>users<\/code>\uff0c\u5176\u4e2d\u6709\u4e00\u500b\u5217 <code>preferences<\/code> \u5b58\u5132\u7528\u6236\u7684\u504f\u597d\u8a2d\u7f6e\uff0c\u9019\u4e9b\u8a2d\u7f6e\u4ee5JSON\u683c\u5f0f\u5b58\u5132\u3002\u5982\u679c\u4f60\u60f3\u63d0\u53d6\u7528\u6236\u7684\u7b2c\u4e00\u500b\u504f\u597d\u8a2d\u7f6e\uff0c\u53ef\u4ee5\u9019\u6a23\u5beb\uff1a<\/p>\n<pre><code>SELECT preferences-&gt;0 AS first_preference\nFROM users\nWHERE user_id = 1;<\/code><\/pre>\n<p>\u5982\u679c <code>preferences<\/code> \u662f\u4e00\u500b\u6578\u7d44\uff0c\u9019\u6a23\u7684\u67e5\u8a62\u5c07\u6703\u5f15\u767c22038\u932f\u8aa4\u3002\u4f60\u53ef\u4ee5\u4f7f\u7528\u4e0a\u8ff0\u7684 <code>CASE<\/code> \u8a9e\u53e5\u4f86\u907f\u514d\u9019\u500b\u554f\u984c\u3002<\/p>\n<h2 id=\"%e7%b8%bd%e7%b5%90-ILosjsnzHX\">\u7e3d\u7d50<\/h2>\n<p>PostgreSQL\u932f\u8aa4\u4ee3\u78bc22038\u901a\u5e38\u662f\u7531\u65bc\u4e0d\u6b63\u78ba\u7684JSON\u6578\u64da\u7d50\u69cb\u6216\u4e0d\u7576\u7684\u51fd\u6578\u4f7f\u7528\u5f15\u8d77\u7684\u3002\u901a\u904e\u6aa2\u67e5\u6578\u64da\u7d50\u69cb\u3001\u4f7f\u7528\u6b63\u78ba\u7684JSON\u51fd\u6578\u4ee5\u53ca\u9069\u7576\u8655\u7406\u591a\u500b\u9805\u76ee\uff0c\u53ef\u4ee5\u6709\u6548\u5730\u4fee\u5fa9\u9019\u500b\u932f\u8aa4\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\">VPS<\/a> \u65b9\u6848\u5c07\u6709\u52a9\u65bc\u63d0\u5347\u6027\u80fd\u548c\u7a69\u5b9a\u6027\uff0c\u7279\u5225\u662f\u5728\u8655\u7406\u8907\u96dc\u7684\u6578\u64da\u7d50\u69cb\u6642\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4fee\u5fa9PostgreSQL\u932f\u8aa4\u4ee3\u78bc22038\u7684\u6307\u5357\uff0c\u89e3\u6c7asingleton_sql_json_item_required\u554f\u984c\uff0c\u78ba\u4fddJSON\u67e5\u8a62\u6b63\u78ba\u57f7\u884c\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-178780","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/178780","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=178780"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/178780\/revisions"}],"predecessor-version":[{"id":178781,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/178780\/revisions\/178781"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=178780"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=178780"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=178780"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}