删除字段出现错误？

[Ivan_pan]

如果某字段存在关系、索引/键或者约束时，删除该字段就会出错，请问怎样取得该字段的所有关系、索引/键或者约束，然后把他们删除，再把该字段删除？在线等待，很急！！！！

[zjcxc]

--删除索引的语句搞错了,重试下面的这个:

--删除某字段的所有关系

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
join syscomments c on a.cdefault=c.id
join sysobjects d on c.id=d.id
where b.name='表名'
and a.name='字段名'
union all --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
join sysobjects e on e.id=a.rkeyid
join syscolumns f on f.id=e.id and a.rkey=f.colid
where e.name='表名'
and d.name='字段名'
union all --索引
select 'drop index ['+c.name+'].['+a.name+']'
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<>'dtproperties'
join syscolumns d on b.id=d.id and b.colid=d.colid
where a.indid not in(0,255)
and c.name='表名'
and d.name='字段名'

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

[Ivan_pan]

还是有问题：
服务器: 消息 3723，级别 16，状态 4，行 1
不允许对索引 'ken.PK_ken' 显式地使用 DROP INDEX。该索引正用于 PRIMARY KEY 约束的强制执行。
邹建兄麻烦再改一下。在线等待！拜托

[zjcxc]

--删除索引的语句搞错了,重试下面的这个:

--删除某字段的所有关系

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
join syscomments c on a.cdefault=c.id
join sysobjects d on c.id=d.id
where b.name='表名'
and a.name='字段名'
union all --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
join sysobjects e on e.id=a.rkeyid
join syscolumns f on f.id=e.id and a.rkey=f.colid
where e.name='表名'
and d.name='字段名'
union all --索引
select case e.xtype when 'PK' 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<>'dtproperties'
join syscolumns d on b.id=d.id and b.colid=d.colid
join sysobjects e on c.id=e.parent_obj
where a.indid not in(0,255)
and c.name='a'
and d.name='id'

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

[zjcxc]

--删除指定表指定字段的所有关系

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
join syscomments c on a.cdefault=c.id
join sysobjects d on c.id=d.id
where b.name='表名'
and a.name='字段名'
union all --索引
select 'drop index ['+a.name+']'
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<>'dtproperties'
join syscolumns d on b.id=d.id and b.colid=d.colid
where a.indid not in(0,255)
and c.name='表名'
and d.name='字段名'
union all --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
join sysobjects e on e.id=a.rkeyid
join syscolumns f on f.id=e.id and a.rkey=f.colid
where e.name='表名'
and d.name='字段名'

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

[zjcxc]

注意修改上述语句中的"表名"为你要处理的表名
字段名改为你要删除的字段名.

执行完上述语句后,再执行删除字段的语句:
alter table 表 drop column 字段

[Ivan_pan]

运行后出现：对于 DROP INDEX，必须以 tablename.indexname 的形式同时给出表名和索引名。请问怎么回事？

[Ivan_pan]

执行alter table 表 drop column 字段 后出现错误
服务器: 消息 5074，级别 16，状态 8，行 31
对象 'PK_ken' 依赖于 列 'pkid'。
服务器: 消息 4922，级别 16，状态 1，行 31
ALTER TABLE DROP COLUMN pkid 失败，因为有一个或多个对象访问此列。

[Ivan_pan]

谢谢邹建兄，问题解决了！分全给你了！