From: Együd Csaba <csegyud@freemail.hu>
To: pgsql-sql@postgresql.org
Subject: Re: Getting all rows even if not a member of any groups
Date: Wed, 02 Jul 2003 12:00:48 +0200
Message-ID: <010601c34080$d8488a10$230a0a0a@compaq> (raw)
References: <11362.1056313692@www59.gmx.net>
<00bd01c33c9d$1b584e90$230a0a0a@compaq>
<20030627140854.GA15269@wolff.to>
<00e501c33cb6$f4cc4cd0$230a0a0a@compaq>
<20030627151025.GE15269@wolff.to>
Dear All,
thank you for your help, it was really efficient.
I'll get by with it now. Thanks.
-- Csaba
----- Original Message -----
From: "Bruno Wolff III" <bruno@wolff.to>
To: "Együd Csaba" <csegyud@freemail.hu>
Cc: <pgsql-sql@postgresql.org>
Sent: Friday, June 27, 2003 5:10 PM
Subject: Re: [SQL] Getting all rows even if not a member of any groups
> On Fri, Jun 27, 2003 at 16:18:10 +0200,
> Együd Csaba <csegyud@freemail.hu> wrote:
> >
> > This is absolutelly what I want, but I can't understand how it is
working.
> > Where can I find a descriptive (tale-like, for kids ... :) )
documentation
> > about using joins?
>
> If you look at the documentation for the select command and page down a
> bit there is a description of join syntax. Note that in 7.4 using
> the explicit join syntax won't force join order. (This really only
> affects cross joins and inner joins; left and right joins normally
> can't be reordered.)
>
> You need a left join to pick up products that aren't in any group.
> The parenthesis changed the join order so that group names were attached
> to group ids before group ids were joined to products. This can have
> performance implications. I think that this is probably the faster
> way, but the other option would to have been to make the second join
> a left join as well.
>
>
>
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To: pgsql-sql@postgresql.org
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Subject: Re: Getting all rows even if not a member of any groups
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