{"id":125,"date":"2024-10-30T17:50:39","date_gmt":"2024-10-30T09:50:39","guid":{"rendered":"https:\/\/zhoujibin.com\/?p=125"},"modified":"2024-10-30T17:50:40","modified_gmt":"2024-10-30T09:50:40","slug":"pg%e5%b8%b8%e7%94%a8%e5%87%bd%e6%95%b0","status":"publish","type":"post","link":"https:\/\/zhoujibin.com\/?p=125","title":{"rendered":"PG\u5e38\u7528\u51fd\u6570"},"content":{"rendered":"\n<h1 class=\"wp-block-heading\">coalesce<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\">\u8bf4\u660e<\/h2>\n\n\n\n<p>\u53d6\u4ece\u5de6\u5230\u53f3\u4e0d\u4e3anull\u7684\u53c2\u6570\u503c<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u793a\u4f8b<\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code>select coalesce(null, 0) from dual;\n-- \u7ed3\u679c\uff1a0\nselect coalesce(null, null, 1) from dual;\n-- \u7ed3\u679c\uff1a1\nselect coalesce(null, null, '', 2) from dual;\n-- \u7ed3\u679c\uff1a''<\/code><\/pre>\n\n\n\n<h1 class=\"wp-block-heading\">cast<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\">\u8bf4\u660e<\/h2>\n\n\n\n<p>\u8f6c\u6362\u67e5\u8be2\u7ed3\u679c\u5bf9\u5e94\u7684\u7c7b\u578b<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u793a\u4f8b<\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code>-- \u8fd4\u56de\u7684\u7ed3\u679c\u662fint\u7c7b\u578b\nselect max(1) from dual;\n-- \u8f6c\u6362\u4e3abigint\uff0c\u8bed\u6cd5 cast(\u6e90\u6570\u636e as \u76ee\u6807\u6570\u636e\u7c7b\u578b)\nselect cast( max(1) as bigint) from dual;<\/code><\/pre>\n\n\n\n<p>\u5176\u4ed6\u7c7b\u578b\u53c2\u8003\uff1a<a href=\"http:\/\/www.postgres.cn\/docs\/14\/datatype.html\">pg\u6570\u636e\u7c7b\u578b (postgres.cn)<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>coalesce \u8bf4\u660e \u53d6\u4ece\u5de6\u5230\u53f3\u4e0d\u4e3anull\u7684\u53c2\u6570\u503c \u793a\u4f8b cast \u8bf4\u660e \u8f6c\u6362\u67e5\u8be2\u7ed3\u679c\u5bf9\u5e94\u7684\u7c7b\u578b \u793a\u4f8b \u5176 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[14],"tags":[28],"class_list":["post-125","post","type-post","status-publish","format-standard","hentry","category-database","tag-pg"],"_links":{"self":[{"href":"https:\/\/zhoujibin.com\/index.php?rest_route=\/wp\/v2\/posts\/125"}],"collection":[{"href":"https:\/\/zhoujibin.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zhoujibin.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zhoujibin.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/zhoujibin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=125"}],"version-history":[{"count":1,"href":"https:\/\/zhoujibin.com\/index.php?rest_route=\/wp\/v2\/posts\/125\/revisions"}],"predecessor-version":[{"id":126,"href":"https:\/\/zhoujibin.com\/index.php?rest_route=\/wp\/v2\/posts\/125\/revisions\/126"}],"wp:attachment":[{"href":"https:\/\/zhoujibin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=125"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zhoujibin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=125"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zhoujibin.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=125"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}