alter table tblNWall_Wall drop CONSTRAINT DF_tblNWall_WallExposureID goAlter Table tblNWall_Wall Alter Column WallExposure varchar(20) default ('') go
先禁用约束..再修改可以吗?alter table tblNWall_Wall nocheck constraint all go alter table tblNWall_Wall alter column WallExposure varchar(20) go alter table tblNWall_Wall check constraint all这样可以吗?
USE tempdb GOCREATE TABLE T1 ( Name nvarchar(20) CONSTRAINT DF_Name DEFAULT('') ) GO--删除约束 ALTER TABLE T1 DROP CONSTRAINT DF_Name GO--修改字段 ALTER TABLE T1 ALTER COLUMN Name varchar(20) GO--添加约束 ALTER TABLE T1 ADD CONSTRAINT DF_Name DEFAULT '' FOR Name GO--检查结果 EXEC SP_HELP 'T1' GO DROP TABLE T1 GO
goAlter Table tblNWall_Wall Alter Column WallExposure varchar(20) default ('')
go
go
alter table tblNWall_Wall alter column WallExposure varchar(20)
go
alter table tblNWall_Wall check constraint all这样可以吗?
USE tempdb
GOCREATE TABLE T1
(
Name nvarchar(20) CONSTRAINT DF_Name DEFAULT('')
)
GO--删除约束
ALTER TABLE T1
DROP CONSTRAINT DF_Name
GO--修改字段
ALTER TABLE T1
ALTER COLUMN Name varchar(20)
GO--添加约束
ALTER TABLE T1
ADD CONSTRAINT DF_Name
DEFAULT '' FOR Name
GO--检查结果
EXEC SP_HELP 'T1'
GO
DROP TABLE T1
GO