{"id":139217,"date":"2024-10-31T18:12:20","date_gmt":"2024-10-31T10:12:20","guid":{"rendered":"https:\/\/server.hk\/cnblog\/139217\/"},"modified":"2024-10-31T18:12:21","modified_gmt":"2024-10-31T10:12:21","slug":"sql-server%e6%95%b8%e6%93%9a%e5%ba%abdefault-value%e7%9a%84%e4%bd%bf%e7%94%a8%e7%b8%bd%e7%b5%90","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/139217\/","title":{"rendered":"SQL Server\u6578\u64da\u5eabdefault value\u7684\u4f7f\u7528\u7e3d\u7d50"},"content":{"rendered":"<h1 id=\"sql-server%e6%95%b8%e6%93%9a%e5%ba%abdefault-value%e7%9a%84%e4%bd%bf%e7%94%a8%e7%b8%bd%e7%b5%90-hhbCnQHqae\">SQL Server\u6578\u64da\u5eabdefault value\u7684\u4f7f\u7528\u7e3d\u7d50<\/h1>\n<p>\u5728SQL Server\u4e2d\uff0cdefault value\uff08\u9810\u8a2d\u503c\uff09\u662f\u4e00\u500b\u975e\u5e38\u91cd\u8981\u7684\u7279\u6027\uff0c\u80fd\u5920\u5e6b\u52a9\u958b\u767c\u8005\u5728\u63d2\u5165\u6578\u64da\u6642\u81ea\u52d5\u586b\u5145\u67d0\u4e9b\u6b04\u4f4d\u7684\u503c\u3002\u9019\u4e0d\u50c5\u63d0\u9ad8\u4e86\u6578\u64da\u7684\u5b8c\u6574\u6027\uff0c\u9084\u7c21\u5316\u4e86\u6578\u64da\u63d2\u5165\u7684\u904e\u7a0b\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0eSQL Server\u4e2ddefault value\u7684\u4f7f\u7528\uff0c\u5305\u62ec\u5176\u5b9a\u7fa9\u3001\u8a2d\u7f6e\u65b9\u6cd5\u3001\u61c9\u7528\u5834\u666f\u53ca\u6ce8\u610f\u4e8b\u9805\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%afdefault-value%ef%bc%9f-hhbCnQHqae\">\u4ec0\u9ebc\u662fDefault Value\uff1f<\/h2>\n<p>Default value\u662f\u6307\u5728\u63d2\u5165\u65b0\u8a18\u9304\u6642\uff0c\u5982\u679c\u67d0\u500b\u6b04\u4f4d\u672a\u88ab\u660e\u78ba\u6307\u5b9a\u503c\uff0c\u5247\u81ea\u52d5\u4f7f\u7528\u7684\u503c\u3002\u9019\u5c0d\u65bc\u67d0\u4e9b\u6b04\u4f4d\u4f86\u8aaa\u662f\u975e\u5e38\u6709\u7528\u7684\uff0c\u4f8b\u5982\u5275\u5efa\u6642\u9593\u3001\u72c0\u614b\u6a19\u8a18\u7b49\u3002<\/p>\n<h2 id=\"%e5%a6%82%e4%bd%95%e8%a8%ad%e7%bd%aedefault-value-hhbCnQHqae\">\u5982\u4f55\u8a2d\u7f6eDefault Value<\/h2>\n<p>\u5728SQL Server\u4e2d\uff0c\u53ef\u4ee5\u5728\u5275\u5efa\u8868\u6642\u6216\u4fee\u6539\u8868\u7d50\u69cb\u6642\u8a2d\u7f6edefault value\u3002\u4ee5\u4e0b\u662f\u8a2d\u7f6edefault value\u7684\u57fa\u672c\u8a9e\u6cd5\uff1a<\/p>\n<pre><code>CREATE TABLE \u8868\u540d (\n    \u6b04\u4f4d1 \u6578\u64da\u985e\u578b DEFAULT \u9810\u8a2d\u503c,\n    \u6b04\u4f4d2 \u6578\u64da\u985e\u578b DEFAULT \u9810\u8a2d\u503c\n);<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u5275\u5efa\u4e00\u500b\u7528\u6236\u8868\uff0c\u4e26\u70ba\u8a3b\u518a\u6642\u9593\u8a2d\u7f6e\u9810\u8a2d\u503c\uff1a<\/p>\n<pre><code>CREATE TABLE Users (\n    UserID INT PRIMARY KEY,\n    UserName NVARCHAR(50),\n    RegistrationDate DATETIME DEFAULT GETDATE()\n);<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c\u7576\u63d2\u5165\u65b0\u7528\u6236\u6642\uff0c\u5982\u679c\u672a\u63d0\u4f9bRegistrationDate\u7684\u503c\uff0c\u5247\u6703\u81ea\u52d5\u4f7f\u7528\u7576\u524d\u65e5\u671f\u548c\u6642\u9593\u3002<\/p>\n<h2 id=\"%e4%bf%ae%e6%94%b9%e7%8f%be%e6%9c%89%e8%a1%a8%e7%9a%84default-value-hhbCnQHqae\">\u4fee\u6539\u73fe\u6709\u8868\u7684Default Value<\/h2>\n<p>\u5982\u679c\u9700\u8981\u70ba\u5df2\u5b58\u5728\u7684\u8868\u6dfb\u52a0\u6216\u4fee\u6539default value\uff0c\u53ef\u4ee5\u4f7f\u7528ALTER TABLE\u8a9e\u53e5\u3002\u4ee5\u4e0b\u662f\u4fee\u6539default value\u7684\u8a9e\u6cd5\uff1a<\/p>\n<pre><code>ALTER TABLE \u8868\u540d\nADD CONSTRAINT \u7d04\u675f\u540d DEFAULT \u9810\u8a2d\u503c FOR \u6b04\u4f4d\u540d;<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u70baUsers\u8868\u7684UserName\u6b04\u4f4d\u8a2d\u7f6e\u4e00\u500b\u9810\u8a2d\u503c\uff1a<\/p>\n<pre><code>ALTER TABLE Users\nADD CONSTRAINT DF_UserName DEFAULT 'Guest' FOR UserName;<\/code><\/pre>\n<h2 id=\"default-value%e7%9a%84%e6%87%89%e7%94%a8%e5%a0%b4%e6%99%af-hhbCnQHqae\">Default Value\u7684\u61c9\u7528\u5834\u666f<\/h2>\n<ul>\n<li><strong>\u81ea\u52d5\u586b\u5145\u6642\u9593\u6233\uff1a<\/strong>\u5728\u8a18\u9304\u5275\u5efa\u6216\u66f4\u65b0\u6642\uff0c\u81ea\u52d5\u586b\u5145\u7576\u524d\u6642\u9593\u3002<\/li>\n<li><strong>\u72c0\u614b\u6a19\u8a18\uff1a<\/strong>\u70ba\u67d0\u4e9b\u72c0\u614b\u6b04\u4f4d\u8a2d\u7f6e\u9810\u8a2d\u503c\uff0c\u4f8b\u5982\u201c\u555f\u7528\u201d\u6216\u201c\u7981\u7528\u201d\u3002<\/li>\n<li><strong>\u7c21\u5316\u6578\u64da\u63d2\u5165\uff1a<\/strong>\u5728\u63d2\u5165\u6578\u64da\u6642\uff0c\u6e1b\u5c11\u5fc5\u586b\u6b04\u4f4d\u7684\u6578\u91cf\uff0c\u5f9e\u800c\u7c21\u5316\u64cd\u4f5c\u3002<\/li>\n<\/ul>\n<h2 id=\"%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-hhbCnQHqae\">\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5728\u4f7f\u7528default value\u6642\uff0c\u9700\u8981\u6ce8\u610f\u4ee5\u4e0b\u5e7e\u9ede\uff1a<\/p>\n<ul>\n<li>\u9810\u8a2d\u503c\u53ea\u80fd\u5728\u63d2\u5165\u65b0\u8a18\u9304\u6642\u751f\u6548\uff0c\u5c0d\u65bc\u5df2\u5b58\u5728\u7684\u8a18\u9304\u4e0d\u6703\u81ea\u52d5\u66f4\u65b0\u3002<\/li>\n<li>\u5982\u679c\u63d2\u5165\u7684\u6578\u64da\u660e\u78ba\u6307\u5b9a\u4e86\u67d0\u500b\u6b04\u4f4d\u7684\u503c\uff0c\u5247\u9810\u8a2d\u503c\u4e0d\u6703\u88ab\u4f7f\u7528\u3002<\/li>\n<li>\u5728\u8a2d\u7f6e\u9810\u8a2d\u503c\u6642\uff0c\u9700\u78ba\u4fdd\u5176\u7b26\u5408\u8a72\u6b04\u4f4d\u7684\u6578\u64da\u985e\u578b\u548c\u7d04\u675f\u689d\u4ef6\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b5%90%e8%ab%96-hhbCnQHqae\">\u7d50\u8ad6<\/h2>\n<p>SQL Server\u4e2d\u7684default value\u662f\u4e00\u500b\u5f37\u5927\u7684\u529f\u80fd\uff0c\u80fd\u5920\u5e6b\u52a9\u958b\u767c\u8005\u63d0\u9ad8\u6578\u64da\u7684\u5b8c\u6574\u6027\u548c\u63d2\u5165\u6548\u7387\u3002\u901a\u904e\u5408\u7406\u8a2d\u7f6e\u9810\u8a2d\u503c\uff0c\u53ef\u4ee5\u7c21\u5316\u6578\u64da\u64cd\u4f5c\uff0c\u6e1b\u5c11\u932f\u8aa4\u767c\u751f\u7684\u6a5f\u6703\u3002\u5728\u5be6\u969b\u61c9\u7528\u4e2d\uff0c\u958b\u767c\u8005\u61c9\u6839\u64da\u5177\u9ad4\u9700\u6c42\u9078\u64c7\u5408\u9069\u7684\u9810\u8a2d\u503c\uff0c\u4e26\u6ce8\u610f\u76f8\u95dc\u7684\u7d04\u675f\u689d\u4ef6\u3002<\/p>\n<p>\u5982\u9700\u4e86\u89e3\u66f4\u591a\u95dc\u65bc\u6578\u64da\u5eab\u7ba1\u7406\u548c\u96f2\u7aef\u6280\u8853\u7684\u8cc7\u8a0a\uff0c\u8acb\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9<a href=\"https:\/\/server.hk\">Server.HK<\/a>\uff0c\u6211\u5011\u63d0\u4f9b\u5404\u985e<em>VPS<\/em>\u548c<em>\u9999\u6e2f\u4f3a\u670d\u5668<\/em>\u89e3\u6c7a\u65b9\u6848\uff0c\u52a9\u60a8\u8f15\u9b06\u7ba1\u7406\u6578\u64da\u5eab\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3SQL Server\u6578\u64da\u5eab\u4e2ddefault value\u7684\u4f7f\u7528\u65b9\u6cd5\u8207\u6700\u4f73\u5be6\u8e10\uff0c\u63d0\u5347\u6578\u64da\u7ba1\u7406\u6548\u7387\u8207\u4e00\u81f4\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-139217","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/139217","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=139217"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/139217\/revisions"}],"predecessor-version":[{"id":139218,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/139217\/revisions\/139218"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=139217"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=139217"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=139217"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}