Re: selecting rows tagged with "a" but not "b" - Mailing list pgsql-sql

Hi Darrell,

SELECT DISTINCT articleID FROM tags WHERE tag = "a" 
EXCEPT
SELECT DISTINCT articleID FROM tags WHERE tag = "b";

Regards,

Andreas

-----Ursprüngliche Nachricht-----
Von: pgsql-sql-owner@postgresql.org [mailto:pgsql-sql-owner@postgresql.org] Im Auftrag von 8q5tmkyqry@sneakemail.com
Gesendet: Montag, 1. Februar 2010 14:32
An: pgsql-sql@postgresql.org
Betreff: [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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