如何在SQL Server中删除外键?

我已经创build了一个外键(在SQL Server中):

alter table company add CountryID varchar(3); alter table company add constraint Company_CountryID_FK foreign key(CountryID) references Country; 

然后我运行这个查询:

 alter table company drop column CountryID; 

我得到这个错误:

消息5074,级别16,状态4,行2
对象“Company_CountryID_FK”依赖于“CountryID”列。
消息4922号,16楼,9号,2号线
ALTER TABLE DROP COLUMN CountryID失败,因为一个或多个对象访问此列

我已经尝试过,但似乎没有工作:

 alter table company drop foreign key Company_CountryID_FK; alter table company drop column CountryID; 

我需要做些什么来删除CountryID列?

谢谢。

尝试

 alter table company drop constraint Company_CountryID_FK alter table company drop column CountryID 

这将工作:

 ALTER TABLE [dbo].[company] DROP CONSTRAINT [Company_CountryID_FK] 

我认为这对你有帮助

 DECLARE @ConstraintName nvarchar(200) SELECT @ConstraintName = KCU.CONSTRAINT_NAME FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS AS RC INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS KCU ON KCU.CONSTRAINT_CATALOG = RC.CONSTRAINT_CATALOG AND KCU.CONSTRAINT_SCHEMA = RC.CONSTRAINT_SCHEMA AND KCU.CONSTRAINT_NAME = RC.CONSTRAINT_NAME WHERE KCU.TABLE_NAME = 'TABLE_NAME' AND KCU.COLUMN_NAME = 'TABLE_COLUMN_NAME' IF @ConstraintName IS NOT NULL EXEC('alter table TABLE_NAME drop CONSTRAINT ' + @ConstraintName) 

它将根据特定的表和列删除外键约束。

首先检查约束的存在,然后放下它。

 if exists (select 1 from sys.objects where name = 'Company_CountryID_FK' and type='F') begin alter table company drop constraint Company_CountryID_FK end 
 alter table company drop constraint Company_CountryID_FK 

我不知道MSSQL,但它不会是:

 alter table company drop **constraint** Company_CountryID_FK; 

您也可以右键单击表格,select修改,然后转到属性,右键单击它,然后select删除主键。

你想要放弃FK约束或列本身?

删除约束:

 alter table company drop constraint Company_CountryID_FK 

删除约束之前,您将无法删除该列。