Re: Should be easy enough to get this result (or is it possible?)...

> > I think the following code explains my problem more elegantly than I
> > could ever hope to try and explain in a reasonable amount of words.
> > The upshot of things being that I want the 2nd query below (f.foo =
> > 'b') to return foo_id and foo.  Am I missing something?  My head
> > stands poised to get clobbered with the clue-bat. Here's the test
> > case:
> >
> > CREATE TABLE foo ( foo_id SERIAL NOT NULL, foo VARCHAR(32) NOT NULL );
> > CREATE TABLE bar ( bar_id SERIAL NOT NULL, foo_id INT NOT NULL, bar VARCHAR(32) NOT NULL);
> > INSERT INTO foo (foo) VALUES ('a');
> > INSERT INTO foo (foo) VALUES ('b');
> > INSERT INTO foo (foo) VALUES ('c');
> > INSERT INTO bar (foo_id, bar) VALUES ('1','x');
> > INSERT INTO bar (foo_id, bar) VALUES ('1','y');
> > INSERT INTO bar (foo_id, bar) VALUES ('1','z');
> > INSERT INTO bar (foo_id, bar) VALUES ('2','x');
> > INSERT INTO bar (foo_id, bar) VALUES ('2','z');
> >
> > SELECT f.foo_id, f.foo, b.bar_id, b.bar
> > FROM foo AS f LEFT JOIN bar AS b on (f.foo_id = b.foo_id)
> > WHERE (b.bar ISNULL OR b.bar = 'y') AND f.foo = 'b';
> >  foo_id | foo | bar_id | bar
> > --------+-----+--------+-----
> > (0 rows)
>
> I think you want something like (not completely tested):
> SELECT f.foo_id, f.foo, b.bar_id, b.bar
> from foo as f left join
> (select * from bar b where b.bar='y' or b.bar is null) as b
> on (f.foo_id=b.foo_id) where f.foo='b';
>
> You want to limit the bar rows you're left joining to, not
> the rows from the output of the join I think.

Cha-ching!  Yeah, you successfully clubbed me w/ the clue-bat: left
join on a sub-select gave me exactly what I wanted: thank you.  -sc

--
Sean Chittenden