Chris <dmagick@gmail.com> writes:
> eg mysql doesn't force you to group by all columns being selected - I
> can do:
> select field1, field2, field3 from table group by field1;
> and have it valid in mysql (but of course postgres will tell you it's
> not valid and need to add grouping for field2 and field3).
Actually, that *is* legal per SQL99 under certain specified conditions
(eg if field1 is a primary key for table). We haven't gotten around to
implementing SQL99's relaxed rules for grouping --- we're still
basically doing what SQL92 says. Now the full SQL99 spec for this is
pretty hairy, but I'd bet lunch that mysql supports only the easier
cases such as group-by-primary-key. We might be able to cover the same
cases they do without too much sweat ... does anyone want to dig in and
determine exactly which cases they cover?
regards, tom lane
