From: Yeb Havinga <yebhavinga@gmail.com>
To: pgsql-sql@postgresql.org
Subject: Re: selecting rows tagged with "a" but not "b"
Date: Mon, 01 Feb 2010 15:52:36 +0100
Message-ID: <4B66EAB4.4020900@gmail.com> (raw)
In-Reply-To: <20100201141453.GA8857@tux>
References: <11366-1265031099-334353@sneakemail.com>
<20100201141453.GA8857@tux>
Andreas Kretschmer wrote:
> 8q5tmkyqry@sneakemail.com <8q5tmkyqry@sneakemail.com> wrote:
>
>
>> Hi,
>>
>> I have a two tables:
>>
>> article
>> articleID, name, content
>>
>> tags
>> articleID, tag
>>
>> I want to find all articles that are tagged with "a" but not "b"
>>
>> how do I do this?
>>
>
> select a.* from article left join tags t on a.articleID=t.articleID where b.tag = 'a';
>
select a.* from article left join tags t on a.articleID=t.articleID
where t.tag = 'a'
where not exists (select * from tags t2 where t2.articleID=a.articleID
and t2.tag = 'b');
Yeb
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To: pgsql-sql@postgresql.org
Cc: yebhavinga@gmail.com
Subject: Re: selecting rows tagged with "a" but not "b"
In-Reply-To: <4B66EAB4.4020900@gmail.com>
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