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From: "Dan Langille" <dan@langille.org>
To: Josh Berkus <josh@agliodbs.com>
Date: Sat, 27 Sep 2003 08:38:27 -0400
MIME-Version: 1.0
Subject: Re: Removing simliar elements from a set
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On 26 Sep 2003 at 16:55, Josh Berkus wrote:

> Dan, 
> 
> > I'm trying to remove items from a set which are similar to items in
> > another set.
> <snip>
> 
> > In short, we remove all items from MASTER which are under the directories
> > specified in MATCHES.
> 
> from your example, you are trying to remove all directories which do *not* 
> match.   What do you want, exactly?

Josh and I talked on IRC about this.

This is the result set I want:

 /ports/Mk/bsd.python.mk

I want things from MASTER which do not match things in MATCHES.

Josh suggested this:

SELECT * 
  FROM master 
 WHERE NOT EXISTS (
   SELECT *
     FROM matches 
     WHERE master.pathname LIKE (matches.pathname || '/%'));

Cheers.
-- 
Dan Langille : http://www.langille.org/