SQLServer中新增字段之存储过程

CREATE PROCEDURE [dbo].[ProcSys_UpdURtsTbl] (@Mdl nvarchar(16)) AS
if @Mdl='' return

declare @Tbln nvarchar(20)
set @Tbln= @Mdl + '_Users'
declare tb cursor local
for select 'if not exists(select name from syscolumns where (id=object_id(N'''+@Tbln+''')) and (name=N'''+a.RtsName+''')) ALTER TABLE ['+@Tbln+'] Add '+a.RtsName+' bit default(0) null' from System_MdlsRts a Where (MdlName=@Mdl)
declare @s Nvarchar(4000)
open tb
fetch next from tb into @s
while @@fetch_status=0
begin
 exec(@s)
 fetch next from tb into @s
end
close tb
deallocate tb
GO