Re: Existential quantifier

From: Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com>
To: Dag-Erling Smørgrav <des(at)des(dot)no>
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: Existential quantifier
Date: 2009-10-10 00:26:20
Message-ID: 20091009172456.C81911@megazone.bigpanda.com
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On Sat, 10 Oct 2009, [utf-8] Dag-Erling Smrgrav wrote:

> Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com> writes:
> > Not at all tested as I don't have access to my db right now, but I think
> > something like one of these would work:
> >
> > select fs.film.title, fs.film.year
> > from fs.film
> > where exists(select 1 from fs.star where fs.film.id = fs.star.film
> > and fs.star.last = 'Sheen');
>
> Ah, that was exactly what I was looking for.
>
> > select fs.film.title, fs.film.year
> > from fs.film
> > where fs.film.id in (select fs.star.film where fs.star.last = 'Sheen');
>
> ITYM
>
> select fs.film.title, fs.film.year
> from fs.film
> where fs.film.id in (
> select fs.star.film from fs.star where fs.star.last = 'Sheen'
> );
>
> (missing FROM)

Yeah, that'd be necessary. You might want to try them on a realistic data
set to see how the various options are planned.

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