SQL Server and .NET Typed Dataset AllowDBNull Metadata

Question

Good afternoon,

I am generating a typed dataset from a stored procedure. The stored procedure may contain something like:

select t1.colA, t2.colA AS t2colA 
from t1 
  inner join t2 
    on t1.key = t2.key 

When I generate the typed dataset, the dataset knows whether t1.colA allows NULLs, but it always puts FALSE in AllowDBNull for t2.colA even if t2.colA allows NULL.

Is this because the column is aliased? Is there any way, from SQL, to hint to VS that the column allows NULL? We currently have to go in and update the column's AllowDBNull if we regenerate the table.

Thanks in advance.

Christian