On Tue, Jan 09, 2007 at 08:28:29 -0500,
Chander Ganesan <chander@otg-nc.com> wrote:
> It would. A query that uses an inner join implies that a matching entry
> must exist in both tables - so the join must occur, otherwise you could
> be returning rows that don't satisfy the join condition.
While this might not be worth doing, a foreign key constraint could be used
to establish the existance of the matching row, so that you wouldn't actually
need to look in the other table to verify that if you didn't need any of the
other columns in the other table. There will be some tricky cases for this,
such as when there are deferred constraints or when updating the foreign key
field.