create proc addcolumn @tablename varchar(30), --表名 @colname varchar(30), --要加的列名 @coltype varchar(100), --要加的列類型 @colid int --加到第幾列 as
declare @colid_max int declare @sql varchar(1000) --動態sql語句 -------------------------------------------------- if not exists(select 1 from sysobjects where name = @tablename and xtype = 'u') begin raiserror 20001 '沒有這個表' return -1 end -------------------------------------------------- if exists(select 1 from syscolumns where id = object_id(@tablename) and name = @colname) begin raiserror 20002 '這個表已經有這個列了！' return -1 end -------------------------------------------------- --保證該表的colid是連續的 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 '加一個新列不成功，請檢查你的列類型是否正確' return -1 end -------------------------------------------------- --打開修改系統表的開關 EXEC sp_configure 'allow updates',1 RECONFIGURE WITH OVERRIDE
--將新列列號暫置為-1 set @sql = 'update syscolumns set colid = -1 where id = object_id('''+@tablename+''') and colid = '+cast(@colid_max as varchar(10)) exec(@sql)
--將其他列的列號加1 set @sql = 'update syscolumns set colid = colid + 1 where id = object_id('''+@tablename+''') and colid >= '+cast(@colid as varchar(10)) exec(@sql)
--將新列列號復位 set @sql = 'update syscolumns set colid = '+cast(@colid as varchar(10))+' where id = object_id('''+@tablename+''') and name = '''+@colname +'''' exec(@sql) -------------------------------------------------- --關閉修改系統表的開關 EXEC sp_configure 'allow updates',0 RECONFIGURE WITH OVERRIDE go
