Re: SQL question re aggregates & joins

> You can't include an aggregate in the select if you don't group by
> non-aggregates, so it should be:
>
> select max(t1."When"), t1."Pt_Id", t2."DateOfBirth"
> from "PtStaffAccess" t1, "Person" t2
> where t1."Pt_Id" = t2.id
> group by t1."Pt_Id", t2."DateOfBirth";

I was aware that I could alternatively group by all the columns, but that
actually just highlights the redundancy even more--consider your second
example:

select max(t1."When"), t2.id , t2."DateOfBirth"
from "PtStaffAccess" t1, "Person" t2
where t1."Pt_Id" = t2.id
group by t2.id, t2."DateOfBirth";

Given that t2.id is the primary key, grouping by any other column of t2 is
really redundant. I know *what* SQL won't allow me to do, I'm interested in
knowing if there's some reason *why* other than historical...

--
Scott Ribe
scott_ribe(at)killerbytes(dot)com
http://www.killerbytes.com/
(303) 722-0567 voice