如何用SQL语句将某字段属性不许为空变成允许为空? 如何将某字段设置为主键?
------解决方案--------------------
drop table tbtest
go
create table tbtest(id int)
1.设置为不可为空
ALTER TABLE tbtest ALTER COLUMN id INT NULL
2.设置ID为主键,前提是ID不可为空
ALTER TABLE dbo.tbtest ADD CONSTRAINT
PK_tbtest PRIMARY KEY CLUSTERED
(
id
) ON [PRIMARY]
------解决方案--------------------
ALTER TABLE [dbo].[表名] WITH NOCHECK ADD
CONSTRAINT [PK_主鍵字段] PRIMARY KEY CLUSTERED
(
[主鍵字段]
) ON [PRIMARY]
GO