为什么建立字段时，会出现默认的约束，怎么才能在删除字段的同时，先删除约束。

[netvsj2ee]

谢谢大家，请帮忙

[631799]

--删除指定表中的指定列的约束
CREATE PROCEDURE P_DelConstraint

@table_name varchar(50), --表名
@col_name varchar(50) --列名

AS
declare @tbname sysname,@fdname sysname
select @tbname=@table_name --要处理的表名
,@fdname=@col_name --要处理的字段名

--定义删除处理的语句
declare tb cursor local for
--默认值约束
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 --外键引用
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 --主键/唯一键/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)

--执行删除
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




GO

[netvsj2ee]

能不能不用存储过程，再删除字段的之前，把默认约束删除

[netvsj2ee]

默认约束名是随机生成的

[mschen]

我觉得删除字段的同时就应该会删除约束呀!

[netvsj2ee]

to：631799(杭州工人)
你好，这个有问题，不能删除～请帮忙