{"id":179016,"date":"2024-11-08T22:18:20","date_gmt":"2024-11-08T14:18:20","guid":{"rendered":"https:\/\/server.hk\/cnblog\/179016\/"},"modified":"2024-11-08T22:18:21","modified_gmt":"2024-11-08T14:18:21","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%9a428c9-generated_always%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/179016\/","title":{"rendered":"\u5982\u4f55\u4fee\u5fa9 PostgreSQL \u932f\u8aa4\u4ee3\u78bc\uff1a428C9 &#8211; generated_always\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%9a428c9-generated_always%ef%bc%9f-hHOtMDrsnu\">\u5982\u4f55\u4fee\u5fa9 PostgreSQL \u932f\u8aa4\u4ee3\u78bc\uff1a428C9 &#8211; generated_always\uff1f<\/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 428C9\uff0c\u9019\u901a\u5e38\u8207\u751f\u6210\u7684\u5217\uff08generated columns\uff09\u6709\u95dc\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e\u9019\u500b\u932f\u8aa4\u7684\u539f\u56e0\u53ca\u5176\u89e3\u6c7a\u65b9\u6848\uff0c\u5e6b\u52a9\u958b\u767c\u8005\u66f4\u6709\u6548\u5730\u7ba1\u7406\u548c\u7dad\u8b77 PostgreSQL \u6578\u64da\u5eab\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%af-generated-columns%ef%bc%9f-hHOtMDrsnu\">\u4ec0\u9ebc\u662f generated columns\uff1f<\/h2>\n<p>\u5728 PostgreSQL \u4e2d\uff0c\u751f\u6210\u7684\u5217\u662f\u4e00\u7a2e\u7279\u6b8a\u7684\u5217\uff0c\u5176\u503c\u662f\u6839\u64da\u5176\u4ed6\u5217\u7684\u503c\u81ea\u52d5\u8a08\u7b97\u5f97\u51fa\u7684\u3002\u9019\u4e9b\u5217\u53ef\u4ee5\u662f\u865b\u64ec\u7684\uff08\u4e0d\u4f54\u7528\u5b58\u5132\u7a7a\u9593\uff09\u6216\u6301\u4e45\u7684\uff08\u4f54\u7528\u5b58\u5132\u7a7a\u9593\uff09\u3002\u4f7f\u7528\u751f\u6210\u7684\u5217\u53ef\u4ee5\u7c21\u5316\u6578\u64da\u7684\u7ba1\u7406\uff0c\u6e1b\u5c11\u91cd\u8907\u6578\u64da\u7684\u5b58\u5132\uff0c\u4e26\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u3002<\/p>\n<h2 id=\"%e9%8c%af%e8%aa%a4%e4%bb%a3%e7%a2%bc-428c9-%e7%9a%84%e5%8e%9f%e5%9b%a0-hHOtMDrsnu\">\u932f\u8aa4\u4ee3\u78bc 428C9 \u7684\u539f\u56e0<\/h2>\n<p>\u932f\u8aa4\u4ee3\u78bc 428C9 \u901a\u5e38\u51fa\u73fe\u5728\u4ee5\u4e0b\u60c5\u6cc1\uff1a<\/p>\n<ul>\n<li>\u5617\u8a66\u5728\u751f\u6210\u7684\u5217\u4e0a\u9032\u884c\u4e0d\u5141\u8a31\u7684\u64cd\u4f5c\uff0c\u4f8b\u5982\u76f4\u63a5\u63d2\u5165\u6216\u66f4\u65b0\u5176\u503c\u3002<\/li>\n<li>\u751f\u6210\u7684\u5217\u7684\u5b9a\u7fa9\u4e0d\u6b63\u78ba\uff0c\u5c0e\u81f4 PostgreSQL \u7121\u6cd5\u6b63\u78ba\u8a08\u7b97\u5176\u503c\u3002<\/li>\n<li>\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528\u4e86\u4e0d\u6b63\u78ba\u7684\u8a9e\u6cd5\uff0c\u5c0e\u81f4 PostgreSQL \u7121\u6cd5\u8b58\u5225\u751f\u6210\u7684\u5217\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%e4%bb%a3%e7%a2%bc-428c9-hHOtMDrsnu\">\u5982\u4f55\u4fee\u5fa9\u932f\u8aa4\u4ee3\u78bc 428C9<\/h2>\n<p>\u4fee\u5fa9\u6b64\u932f\u8aa4\u7684\u5177\u9ad4\u6b65\u9a5f\u5982\u4e0b\uff1a<\/p>\n<h3 id=\"1-%e6%aa%a2%e6%9f%a5%e7%94%9f%e6%88%90%e7%9a%84%e5%88%97%e5%ae%9a%e7%be%a9-hHOtMDrsnu\">1. \u6aa2\u67e5\u751f\u6210\u7684\u5217\u5b9a\u7fa9<\/h3>\n<p>\u9996\u5148\uff0c\u6aa2\u67e5\u751f\u6210\u7684\u5217\u7684\u5b9a\u7fa9\u662f\u5426\u6b63\u78ba\u3002\u78ba\u4fdd\u4f7f\u7528\u4e86\u6b63\u78ba\u7684\u8a9e\u6cd5\u4f86\u5b9a\u7fa9\u751f\u6210\u7684\u5217\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>CREATE TABLE example (\n    id SERIAL PRIMARY KEY,\n    value INT,\n    generated_value INT GENERATED ALWAYS AS (value * 2) STORED\n);<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c<code>generated_value<\/code> \u5217\u7684\u503c\u662f\u6839\u64da <code>value<\/code> \u5217\u81ea\u52d5\u8a08\u7b97\u7684\u3002\u5982\u679c\u5b9a\u7fa9\u4e0d\u6b63\u78ba\uff0c\u5247\u9700\u8981\u91cd\u65b0\u5b9a\u7fa9\u751f\u6210\u7684\u5217\u3002<\/p>\n<h3 id=\"2-%e9%81%bf%e5%85%8d%e7%9b%b4%e6%8e%a5%e6%8f%92%e5%85%a5%e6%88%96%e6%9b%b4%e6%96%b0%e7%94%9f%e6%88%90%e7%9a%84%e5%88%97-hHOtMDrsnu\">2. \u907f\u514d\u76f4\u63a5\u63d2\u5165\u6216\u66f4\u65b0\u751f\u6210\u7684\u5217<\/h3>\n<p>\u751f\u6210\u7684\u5217\u7684\u503c\u662f\u81ea\u52d5\u8a08\u7b97\u7684\uff0c\u56e0\u6b64\u4e0d\u61c9\u8a72\u76f4\u63a5\u63d2\u5165\u6216\u66f4\u65b0\u9019\u4e9b\u5217\u7684\u503c\u3002\u5982\u679c\u9700\u8981\u66f4\u6539\u751f\u6210\u7684\u5217\u7684\u503c\uff0c\u61c9\u8a72\u901a\u904e\u66f4\u6539\u5176\u4f9d\u8cf4\u7684\u5217\u4f86\u5be6\u73fe\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>UPDATE example SET value = 10 WHERE id = 1;<\/code><\/pre>\n<p>\u9019\u6a23\uff0c<code>generated_value<\/code> \u5217\u7684\u503c\u5c07\u81ea\u52d5\u66f4\u65b0\uff0c\u800c\u4e0d\u6703\u5f15\u767c\u932f\u8aa4\u3002<\/p>\n<h3 id=\"3-%e6%aa%a2%e6%9f%a5%e6%9f%a5%e8%a9%a2%e8%aa%9e%e6%b3%95-hHOtMDrsnu\">3. \u6aa2\u67e5\u67e5\u8a62\u8a9e\u6cd5<\/h3>\n<p>\u78ba\u4fdd\u5728\u67e5\u8a62\u4e2d\u6b63\u78ba\u4f7f\u7528\u751f\u6210\u7684\u5217\u3002\u5982\u679c\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528\u4e86\u4e0d\u6b63\u78ba\u7684\u8a9e\u6cd5\uff0c\u53ef\u80fd\u6703\u5c0e\u81f4 PostgreSQL \u7121\u6cd5\u8b58\u5225\u751f\u6210\u7684\u5217\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>SELECT id, value, generated_value FROM example;<\/code><\/pre>\n<p>\u9019\u6a23\u7684\u67e5\u8a62\u61c9\u8a72\u80fd\u5920\u6b63\u5e38\u57f7\u884c\uff0c\u4e26\u8fd4\u56de\u6b63\u78ba\u7684\u7d50\u679c\u3002<\/p>\n<h2 id=\"%e7%b8%bd%e7%b5%90-hHOtMDrsnu\">\u7e3d\u7d50<\/h2>\n<p>PostgreSQL \u932f\u8aa4\u4ee3\u78bc 428C9 \u901a\u5e38\u8207\u751f\u6210\u7684\u5217\u7684\u5b9a\u7fa9\u6216\u4f7f\u7528\u4e0d\u7576\u6709\u95dc\u3002\u901a\u904e\u6aa2\u67e5\u751f\u6210\u7684\u5217\u7684\u5b9a\u7fa9\u3001\u907f\u514d\u76f4\u63a5\u64cd\u4f5c\u751f\u6210\u7684\u5217\u4ee5\u53ca\u78ba\u4fdd\u67e5\u8a62\u8a9e\u6cd5\u6b63\u78ba\uff0c\u53ef\u4ee5\u6709\u6548\u5730\u4fee\u5fa9\u6b64\u932f\u8aa4\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u6578\u64da\u7ba1\u7406\u7684\u958b\u767c\u8005\u4f86\u8aaa\uff0c\u4e86\u89e3\u5982\u4f55\u6b63\u78ba\u4f7f\u7528\u751f\u6210\u7684\u5217\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u7a69\u5b9a\u7684 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u5e6b\u52a9\u60a8\u8f15\u9b06\u7ba1\u7406\u6578\u64da\u5eab\u548c\u61c9\u7528\u7a0b\u5e8f\u3002\u7121\u8ad6\u662f <a href=\"https:\/\/server.hk\">\u4e91\u4f3a\u670d\u5668<\/a> \u9084\u662f <a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a>\uff0c\u6211\u5011\u90fd\u80fd\u6eff\u8db3\u60a8\u7684\u9700\u6c42\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3\u5982\u4f55\u4fee\u5fa9 PostgreSQL \u932f\u8aa4\u4ee3\u78bc 428C9\uff0c\u89e3\u6c7a generated_always \u7684\u554f\u984c\uff0c\u78ba\u4fdd\u6578\u64da\u5eab\u6b63\u5e38\u904b\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-179016","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/179016","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=179016"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/179016\/revisions"}],"predecessor-version":[{"id":179017,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/179016\/revisions\/179017"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=179016"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=179016"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=179016"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}