删除某字段的所有关系_存储过程.sql

很好的sql 文档,可能邦你成为sql 高手

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[p_deletefield]') and OBJECTPROPERTY(id, N'IsProcedure') = 1)
drop procedure [dbo].[p_deletefield]
GO

/*--删除某字段的所有关系及该字段

	删除某字段时,常常因为在该字段上定义了约束/外键/默认值
	导致字段删除失败,此存储过就是删除表中指定字段的这些关系

	修正2004.05发布的删除处理中的错误,同时改原来的处理语句为通用存储过程

--邹建 2004.07(引用请保留此信息)--*/

/*--调用示例
	
	exec p_deletefield '表名','字段名'
--*/
create proc p_deletefield
@tbname sysname,	--要处理的表名
@fdname sysname,	--要处理的字段名
@delfield bit=1		--0只删除关系,1同时删除字段
as
declare hCForEach cursor global 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)

exec sp_msforeach_worker '?'

if @delfield=1
	exec('alter table ['+@tbname+'] drop column ['+@fdname+']')
go