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Re: only last records in subgroups

From: Achilleus Mantzios <achill(at)matrix(dot)gatewaynet(dot)com>
To: Dino Vliet <dino_vliet(at)yahoo(dot)com>
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: only last records in subgroups
Date: 2004-08-17 11:35:04
Message-ID: Pine.LNX.4.44.0408171434210.31368-100000@matrix.gatewaynet.com (view raw or flat)
Thread:
Lists: pgsql-sql
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
> 
> 
> 	
> 		
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-- 
-Achilleus


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