On Sat, Oct 09, 2004 at 01:39:45PM -0700, Andrew Ward wrote: > > I'm running postgres 7.3.2 on linux, and making my > requests from Perl scripts using DBD::Pg. My table > structure is as follows (irrelevant cols removed) > > CREATE TABLE name ( > namecounter integer NOT NULL, > firstmiddle character varying(64) NOT NULL, > lastname character varying(64) NOT NULL, > birthdate date, > hh smallint, > famnu integer, > );
This may not be the fastest query, but it should be quite comprehensible. Lightly tested only on 7.4.5 (do you know why you're not using 7.4.x?). SELECT namecounter -- and whatever other columns you need FROM name outername -- alias so it's clear what the joins do WHERE hh = 1 -- simple case: head of family OR ( hh = 0 -- not a head AND NOT EXISTS ( -- there is no head of this family SELECT namecounter FROM name in1 WHERE hh = 1 AND in1.famnu = outername.famnu) AND birthdate = ( -- this person is as old as the oldest person SELECT MIN(birthdate) FROM name in2 WHERE in2.famnu = outername.famnu) ); Richard ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend