Re: selecting rows tagged with "a" but not "b"

Darrell,

Can you provide a little more information and background on your problem. 
please?

What values can the "tag" column assume? Just "a" and "b" ?

Both?

Please give examples of table contents and desired output, your mail doesn't 
contain enough info to give you more advises

Thank you

Best,
Oliveiros


----- Original Message ----- 
From: <8q5tmkyqry@sneakemail.com>
To: <pgsql-sql@postgresql.org>
Sent: Monday, February 01, 2010 1:31 PM
Subject: [SQL] selecting rows tagged with "a" but not "b"


> 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?
>
> what I'd like to do is:
>
> <wishful thinking>
> select articleID from tags where tag="a"
> SUBTRACT
> select articleID from tags where tab="b"
> </wishful thinking>
>
> how do I do this in real SQL?
>
> thanks
>
> Darrell
>
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