删除未命名的约束

Question

作为一个新手,我创造了一些没有明确名称的外键.

然后我创建了SQL生成的疯狂名字之类的FK__Machines__IdArt__760D22A7.猜猜它们将在不同的服务器上生成不同的名称.

是否有任何好的函数可以删除未命名的FK约束作为参数传递表和相关字段？

Answer 1

要在列上删除单个未命名的默认约束,请使用以下代码:

DECLARE @ConstraintName VARCHAR(256)
SET @ConstraintName = (
     SELECT             obj.name
     FROM               sys.columns col 

     LEFT OUTER JOIN    sys.objects obj 
     ON                 obj.object_id = col.default_object_id 
     AND                obj.type = 'F' 

     WHERE              col.object_id = OBJECT_ID('TableName') 
     AND                obj.name IS NOT NULL
     AND                col.name = 'ColunmName'
)   

IF(@ConstraintName IS NOT NULL)
BEGIN
    EXEC ('ALTER TABLE [TableName] DROP CONSTRAINT ['+@ConstraintName+']')
END

如果你想为默认列做这个,这可能比原始问题更常见,我相信很多人会从Google搜索中找到这个,然后只需更改一行:

obj.type = 'F'

至

obj.type = 'D'

Answer 2

没有内置的过程来完成此任务,但您可以使用information_schema视图中的信息构建自己的过程.

基于表的例子

Create Proc dropFK(@TableName sysname)
as
Begin

Declare @FK sysname
Declare @SQL nvarchar(4000)
Declare crsFK cursor for

select tu.Constraint_Name from 
information_schema.constraint_table_usage TU
LEFT JOIN SYSOBJECTS SO 
ON TU.Constraint_NAME = SO.NAME
where xtype = 'F'
and Table_Name = @TableName
open crsFK
fetch next from crsFK into @FK
While (@@Fetch_Status = 0)
Begin
    Set @SQL = 'Alter table ' + @TableName + ' Drop Constraint ' + @FK
    Print 'Dropping ' + @FK
    exec sp_executesql  @SQL
    fetch next from crsFK into @FK
End
Close crsFK
Deallocate crsFK
End