X-Original-To: pgsql-sql@postgresql.org
Received: from localhost (unknown [64.117.224.193])
	by developer.postgresql.org (Postfix) with ESMTP id 8D2E1923517
	for <pgsql-sql@postgresql.org>; Tue, 20 May 2003 13:19:48 -0400 (EDT)
Received: from developer.postgresql.org ([64.117.224.193])
	by localhost (developer.postgresql.org [64.117.224.193:10024])
	(amavisd-new) with ESMTP id 30524-10 for <pgsql-sql@postgresql.org>;
	Tue, 20 May 2003 13:19:43 -0400 (EDT)
Received: from web41805.mail.yahoo.com (web41805.mail.yahoo.com
	[66.218.93.139])
	by developer.postgresql.org (Postfix) with SMTP id 10E489234CE
	for <pgsql-sql@postgresql.org>; Tue, 20 May 2003 13:19:43 -0400 (EDT)
Message-ID: <20030520171940.63419.qmail@web41805.mail.yahoo.com>
Received: from [129.6.154.168] by web41805.mail.yahoo.com via HTTP;
	Tue, 20 May 2003 10:19:40 PDT
Date: Tue, 20 May 2003 10:19:40 -0700 (PDT)
From: ww zz <ts_999@yahoo.com>
Subject: Re: how to do this query?
To: Stephan Szabo <sszabo@megazone23.bigpanda.com>
Cc: pgsql-sql@postgresql.org
In-Reply-To: <20030520094321.T68048-100000@megazone23.bigpanda.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-Virus-Scanned: by amavisd-new
X-Archive-Number: 200305/394
X-Sequence-Number: 13559

another question is:
if I do left outer join on a few big tables, will it
be very slow?

--- Stephan Szabo <sszabo@megazone23.bigpanda.com>
wrote:
> On Tue, 20 May 2003, ww zz wrote:
> 
> > New to sql and may be a simple question for you:
> >
> > I have four tables
> >
> > sample:   sid, sname
> > make:     sid, mdate
> > measure:  sid, mdate, rid
> > result:   rid, resultdata
> >
> > for a gaven sample it always has a sid and sname,
> but
> > it may or may not have any entries in the other
> > tables, the sample could be measured more than
> once
> > and each measure give a result row.
> > question:
> > how do I do a query that given a sid, it will
> retrieve
> > all the information available in the four tables,
> if
> > there are available. If, for example, all tables
> have
> > some entry for a gave sample it will retreve all
> the
> > information, if the "measure" and "result" are
> empty
> > for that sample it will give only the 'sample' and
> > 'make' information....
> 
> Well, you're not going to get a limited column set,
> but you can
> get NULLs in the non-applicable table columns by
> using outer joins.
> 
> Maybe something like something like
>  select * from
>   sample left outer join make using (sid)
>    left outer join measure using (sid)
>    left outer join result using (rid)
>  where sid=<value>;
> 
> 
> ---------------------------(end of
> broadcast)---------------------------
> TIP 2: you can get off all lists at once with the
> unregister command
>     (send "unregister YourEmailAddressHere" to
majordomo@postgresql.org)


__________________________________
Do you Yahoo!?
The New Yahoo! Search - Faster. Easier. Bingo.
http://search.yahoo.com