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
