Date: Tue, 17 Aug 2004 14:35:04 +0300 (EEST)
From: Achilleus Mantzios <achill@matrix.gatewaynet.com>
To: Dino Vliet <dino_vliet@yahoo.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: only last records in subgroups
In-Reply-To: <20040817104437.93301.qmail@web40110.mail.yahoo.com>
Message-ID: <Pine.LNX.4.44.0408171434210.31368-100000@matrix.gatewaynet.com>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII

O kyrios Dino Vliet egrapse stis Aug 17, 2004 :

> Hi there,
> 
> I'm having hard times with the following query:
> I want to select only the last records from a subgroup
> in a table. But because the subgroup contains
> different number of records for every id, I don't know
> how to specify that. For example, check the following
> table,
> id, day
> x,300
> x,250,
> x,0
> y,250
> y,4
> 
> I only want the records
> x,0 and y,4 but how do I manage this in sql? I was
> hoping for a keyword LAST or so, where I can specify
> that when I've ordered my results with order by, I
> could only get the last of the subgroups (the first
> one is easy because I could use limit 1)
> 

Try,

SELECT min(day),id from reg group by id;
 min | id
-----+----
   4 | y
   0 | x
(2 rows)


> Thanks in advance
> 
> 
> 	
> 		
> __________________________________
> Do you Yahoo!?
> New and Improved Yahoo! Mail - 100MB free storage!
> http://promotions.yahoo.com/new_mail 
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 5: Have you checked our extensive FAQ?
> 
>                http://www.postgresql.org/docs/faqs/FAQ.html
> 

-- 
-Achilleus