From: Stephan Szabo <sszabo@megazone.bigpanda.com>
To: Dag-Erling Smørgrav <des@des.no>
Cc: pgsql-sql@postgresql.org
Subject: Re: Existential quantifier
Date: Fri, 9 Oct 2009 16:06:56 -0700 (PDT)
Message-ID: <20091009160318.J80119@megazone.bigpanda.com> (raw)
In-Reply-To: <86bpkgqiv8.fsf@ds4.des.no>
References: <86bpkgqiv8.fsf@ds4.des.no>
On Sat, 10 Oct 2009, [utf-8] Dag-Erling Smørgrav wrote:
> Consider the attached schema (filmstars.sql), which is a poorly designed
> database of films and actors. The following query gives me a list of
> films in which either Charlie or Martin Sheen starred:
>
> select fs.film.title, fs.film.year
> from fs.film left join fs.star on fs.film.id = fs.star.film
> where fs.star.last = 'Sheen'
> group by fs.film.title, fs.film.year;
>
> Is there a way to do this without the "group by" clause?
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');
select fs.film.title, fs.film.year
from fs.film
where fs.film.id in (select fs.star.film where fs.star.last = 'Sheen');
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To: pgsql-sql@postgresql.org
Cc: sszabo@megazone.bigpanda.com, des@des.no
Subject: Re: Existential quantifier
In-Reply-To: <20091009160318.J80119@megazone.bigpanda.com>
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