Re: join and where clause equivalent ? - Mailing list pgsql-novice

Dmitry Tkach <dmitry@openratings.com> writes:
> Nabil Sayegh wrote:
>> is
>> "SELECT * FROM a JOIN b USING (id_a)"
>> fully equivalent to
>> "SELECT * FROM a, b WHERE a.id_a=b.id_a" ?

> I think, the latter form gives the optimizer more freedom in choosing
> the query path.

In this case they are completely equivalent.  If you had more than two
tables (ie, nested JOIN constructs) then there'd be a difference.  See
http://www.postgresql.org/docs/view.php?version=7.3&idoc=0&file=explicit-joins.html

            regards, tom lane