Message-ID: <4251197C.1060904@archonet.com>
Date: Mon, 04 Apr 2005 11:39:56 +0100
From: Richard Huxton <dev@archonet.com>
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To: "Michael L. Hostbaek" <mich@the-lab.org>
Cc: pgsql-sql@postgresql.org
Subject: Re: select & group by
References: <20050404101647.GJ23648@mich2.itxmarket.com>
In-Reply-To: <20050404101647.GJ23648@mich2.itxmarket.com>
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Michael L. Hostbaek wrote:
> I've got a problem selecting some specific data from my table. Imagine
> the following rows:
> 
> part	| mfg	| qty	| price	| eta	
> ---------------------------------------
> TEST1	 ABC	 10	 100		(No ETA, as item is in stock)
> TEST1	 ABC	 12	 120	 04/04
> TEST2	 CBA	 17	 10	 05/05
> TEST2	 CBA	 10	 20		(No ETA, as item is in stock)
> 
> 
> I'd like my selection to produce the following result:
> 
> part	| mfg	| qty	| qty incoming	| highest price	| eta
> -------------------------------------------------------------
> TEST1	 ABC	 10	 12		 120		 04/04
> TEST2	 CBA	 10	 17		 20		 05/05
> 
> Any clues on how to do this ? I kow the group by part, mfg, max(price) -
> but I do not know how to deal with the splitting up qty and stock qty
> and incoming qty.

How about something like:

SELECT
   aa.part,
   aa.mfg,
   aa.qty,
   bb.qty AS qty_incoming,
   CASE WHEN aa.price > bb.price THEN aa.price ELSE bb.price END AS 
highest_price,
   aa.eta
FROM
  (
    SELECT part,mfg,qty,price FROM mytable WHERE eta IS NOT NULL
  ) aa,
  (
    SELECT part,mfg,qty,price FROM mytable WHERE eta IS NULL
  ) bb
WHERE
   aa.part = bb.part
   AND aa.mfg=bb.mfg
;

This is assuming you only have one row with "eta" set for each 
(part,mfg). If not, you'll have to identify which row you want.

-- 
   Richard Huxton
   Archonet Ltd