标签：span log val img constrain phone nts pen 获取
1、查出该字段的约束名称
SELECT c.name FROM sysconstraints a INNER JOIN syscolumns b on a.colid=b.colid INNER JOIN sysobjects c on a.constid=c.id WHERE a.id=object_id(‘TClass‘) AND b.name=‘PhoneIsOpen‘
2、删除该约束
ALTER TABLE TClass DROP CONSTRAINT DF__TClass__PhoneIsO__51BA1E3A
3、修改默认值约束
ALTER TABLE TClass ADD CONSTRAINT DF__TClass__PhoneIsO__51BA1E3A DEFAULT(1) FOR PhoneIsOpen
4、获取表列的默认值
SELECT SO.NAME AS "Table Name", SC.NAME AS "Column Name", SM.TEXT AS "Default Value" FROM dbo.sysobjects SO INNER JOIN dbo.syscolumns SC ON SO.id = SC.id LEFT JOIN dbo.syscomments SM ON SC.cdefault = SM.id WHERE SO.xtype = ‘U‘ and so.name=‘TClass‘ ORDER BY SO.[name], SC.colid
标签：span log val img constrain phone nts pen 获取
原文地址：http://www.cnblogs.com/zhyue93/p/sql_default.html
