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[数据库]sql 修改字段默认值


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.idLEFT JOIN dbo.syscomments SM ON SC.cdefault = SM.idWHERE SO.xtype = 'U' and so.name='TClass'ORDER BY SO.[name], SC.colid