select top 0 * into b
from a

declare ap scroll cursor for
select name from sysobjects where xtype='U'

declare @tab varchar(200),@sql varchar(5000)

open ap
fetch first from ap into @tab
while(@@FETCH_STATUS<>-1)
begin
 select @sql='alter table ['+@tab+'] add constraint ['
 +name+'] '
 from sys.objects
 where parent_object_id=object_id(@tab) and [type]='PK'

 select @sql=@sql+' primary key('+
 (select cast(
 (select name+','
 from (select distinct c.name
 from sys.indexes a
 inner join sys.index_columns b
 on a.[object_id]=b.[object_id]
 inner join sys.columns c
 on b.[object_id]=c.[object_id]
 and b.index_column_id=c.column_id
 where a.[object_id]=object_id(@tab)
 and a.is_primary_key=1) t
 for xml path('')) as varchar(20)))

 select @sql=left(@sql,len(@sql)-1)+') '
 
 -- 打印
 print @sql

 fetch next from ap into @tab
end

close ap
deallocate ap