From: Dmitry Tkach <dmitry@openratings.com>
To: Dave Dribin <dave-ml@dribin.org>
Cc: pgsql-sql@postgresql.org
Subject: Re: One to many query question
Date: Wed, 30 Jul 2003 17:26:23 -0400
Message-ID: <3F2837FF.7020805@openratings.com> (raw)
In-Reply-To: <20030730193517.GB1383@neo.realtors.org>
References: <20030730193517.GB1383@neo.realtors.org>
Dave Dribin wrote:
>Hi, I'm having trouble with what I think should be an easy query. For
>simplicity, I will use a CD database as an example. Each CD may have
>multiple genres. Here's some sample data:
>
>Artist Title Genres
>---------------------- ------------------------------ ----------------
>Miles Davis Some Kind of Blue Jazz
>Metallica Ride the Lightning Rock
>Chemical Brothers Surrender Electronic
>Radiohead OK Computer Rock, Electronic
>
>For simplicities sake, let's ignore normalization on artist and genre,
>and say the tables look like:
>
>CREATE TABLE cd (
> id integer unique,
> artist varchar(25),
> title varchar(25)
>);
>
>CREATE TABLE cd_genres (
> cd_id integer,
> genre varchar(25)
>);
>
>How do I write a query to find all CDs that are NOT Rock?
>
What about
select * from cd where not exists (select 1 from cd_genres where cd_id
= cd.id and genre='Rock')?
Dima
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To: pgsql-sql@postgresql.org
Cc: dmitry@openratings.com, dave-ml@dribin.org
Subject: Re: One to many query question
In-Reply-To: <3F2837FF.7020805@openratings.com>
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