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 -
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asdeclare @colid_max intdeclare @sql varchar(1000) --动态sql语句--------------------------------------------------if not exists(select 1 from sysobjectswhere name = @tablename and xtype = 'u')beginraiserror 20001 '没有这个表'return -1end--------------------------------------------------if exists(select 1 from syscolumnswhere id = object_id(@tablename) and name = @colname)beginraiserror 20002 '这个表已经有这个列了！'return -1end----------------------------------------------------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 < 1set @colid = @colid + 1--------------------------------------------------set @sql = 'alter table '+@tablename+' add '+@colname+' '+@coltypeexec(@sql)select @colid_max = colidfrom syscolumns where id = object_id(@tablename) and name = @colnameif @@rowcount <> 1beginraiserror 20003 '加一个新列不成功，请检查你的列类型是否正确'return -1end----------------------------------------------------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-1set @sql = 'update syscolumnsset colid = -1where id = object_id('''+@tablename+''')and colid = '+cast(@colid_max as varchar(10))exec(@sql)--将其他列的列号加1set @sql = 'update syscolumnsset colid = colid + 1where id = object_id('''+@tablename+''')and colid >= '+cast(@colid as varchar(10))exec(@sql)--将新列列号复位set @sql = 'update syscolumnsset 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 OVERRIDEgo 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)。
