create procedure dropconstraint
@tb varchar(100),@fd varchar(100)
asdeclare @tbname sysname,@fdname sysname
select @tbname=@tb --要處理的表名
,@fdname=@fd --要處理的欄位名
--定義刪除處理的語句
declare tb cursor local for
--預設值約束
select sql='alter table ['+b.name+'] drop constraint ['+d.name+']'
from syscolumns a
join sysobjects b on a.id=b.id and a.name=@fdname and b.name=@tbname
join syscomments c on a.cdefault=c.id
join sysobjects d on c.id=d.id
union --外來鍵引用
select s='alter table ['+c.name+'] drop constraint ['+b.name+']'
from sysforeignkeys a
join sysobjects b on b.id=a.constid
join sysobjects c on c.id=a.fkeyid
join syscolumns d on d.id=c.id and a.fkey=d.colid and d.name=@fdname
join sysobjects e on e.id=a.rkeyid and e.name=@tbname
join syscolumns f on f.id=e.id and a.rkey=f.colid
union --主鍵/唯一鍵/索引
select case when e.xtype in('pk','uq') then 'alter table ['+c.name+'] drop constraint ['+e.name+']'
else 'drop index ['+c.name+'].['+a.name+']' end
from sysindexes a
join sysindexkeys b on a.id=b.id and a.indid=b.indid
join sysobjects c on b.id=c.id and c.xtype='u' and c.name=@tbname
join syscolumns d on b.id=d.id and b.colid=d.colid and d.name=@fdname
left join sysobjects e on e.id=object_id(a.name)
where a.indid not in(0,255)
--執行刪除
declare @s varchar(8000)
open tb
fetch next from tb into @s
while @@fetch_status=0
begin
exec(@s)
fetch next from tb into @s
end
close tb
deallocate tb
先執行上面的sql語句，建立儲存過程，然後再執行儲存過程即可，如：
--刪除字段約束(表，列)
exec dbo.dropconstraint 'table','minute'
exec dbo.dropconstraint 'table','hour'
exec dbo.dropconstraint 'table','day'
go
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