create proc addcolumn
@tablename varchar(30), --表名
@colname varchar(30), --要加的列名
@coltype varchar(100), --要加的列类型
@colid int --加到第几列
as
declare @colid_max int
declare @sql varchar(1000) --动态sql语句
--------------------------------------------------
if not exists(select 1 from sysobjects
where name = @tablename and xtype = 'u ')
begin
raiserror 20001 '没有这个表 '
return -1
end
--------------------------------------------------
if exists(select 1 from syscolumns
where id = object_id(@tablename) and name = @colname)
begin
raiserror 20002 '这个表已经有这个列了！ '
return -1
end
--------------------------------------------------
--保证该表的colid是连续的
select @colid_max = max(colid) from syscolumns where id=object_id(@tablename)
if @colid > @colid_max or @colid < 1
set @colid = @colid + 1
--------------------------------------------------
set @sql = 'alter table '+@tablename+ ' add '+@colname+ ' '+@coltype
exec(@sql)
select @colid_max = colid
from syscolumns where id = object_id(@tablename) and name = @colname
if @@rowcount <> 1
begin
raiserror 20003 '加一个新列不成功，请检查你的列类型是否正确 '
return -1
end
--------------------------------------------------
--打开修改系统表的开关
EXEC sp_configure 'allow updates ',1 RECONFIGURE WITH OVERRIDE
--将新列列号暂置为-1
set @sql = 'update syscolumns
set colid = -1
where id = object_id( ' ' '+@tablename+ ' ' ')
and colid = '+cast(@colid_max as varchar(10))
exec(@sql)
--将其他列的列号加1
set @sql = 'update syscolumns
set colid = colid + 1
where id = object_id( ' ' '+@tablename+ ' ' ')
and colid > = '+cast(@colid as varchar(10))
exec(@sql)
--将新列列号复位
set @sql = 'update syscolumns
set colid = '+cast(@colid as varchar(10))+ '
where id = object_id( ' ' '+@tablename+ ' ' ')
and name = ' ' '+@colname + ' ' ' '
exec(@sql)
--------------------------------------------------
--关闭修改系统表的开关
EXEC sp_configure 'allow updates ',0 RECONFIGURE WITH OVERRIDE
go
调用方法：
exec addcolumn '表名 ', '新列名 ', '新列类型 ',加到第几个位置
如：
exec addcolumn 'test ', 'id2 ', 'char(10) ',2
表示将id2这个列加到表test的第二个位置，类型是char(10)。