On Fri, Aug 12, 2005 at 18:57:34 +0100, Nick Stone <[EMAIL PROTECTED]> wrote: > Hope this helps > > SELECT > * > FROM > speed_history as outside etc.. > WHERE > (speed = ( > SELECT > speed > FROM > speed_history as inside etc.. > WHERE > (outside.interface = inside.interface) > LIMIT 1 > ORDER BY > speed DESC > ) > ) > > Hopefully you get the idea - basically it's a corelated sub-query - very > useful >
Note that you want to order by interface DESC, speed DESC in the subselect and have an index on (interface, speed) for this to really be efficient. I think 8.1 might be smart enough to use an index on (interface, speed) in the above case, but currently released versions won't. ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq