From: | Oliver Elphick <olly(at)lfix(dot)co(dot)uk> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Yudie <yudie(at)axiontech(dot)com>, pgsql-sql(at)postgresql(dot)org |
Subject: | Re: How to re-sort a sorted query? |
Date: | 2004-10-26 21:57:53 |
Message-ID: | 1098827873.2414.47.camel@linda |
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Lists: | pgsql-sql |
On Tue, 2004-10-26 at 17:43 -0400, Tom Lane wrote:
> Oliver Elphick <olly(at)lfix(dot)co(dot)uk> writes:
> > On Tue, 2004-10-26 at 14:23 -0500, Yudie wrote:
> >> Then I do this query to get unique store number and also the cheapest
> >> price from each store:
> >>
> >> SQL= "Select distinct on (storenumber), itemsku, storenumber,price
> >> from storeproduct where itemsku='10001'
> >> order by storenumber, price"
>
> > That won't get you the cheapest price,
>
> Sure it will. It's a perfectly good application of DISTINCT ON.
> However, he has to use that particular ORDER BY to get the answers
> he wants.
Ah - because ORDER BY is applied before DISTINCT ON; I hadn't realised
that.
--
Oliver Elphick olly(at)lfix(dot)co(dot)uk
Isle of Wight http://www.lfix.co.uk/oliver
GPG: 1024D/A54310EA 92C8 39E7 280E 3631 3F0E 1EC0 5664 7A2F A543 10EA
========================================
"Whosoever therefore shall be ashamed of me and of my
words in this adulterous and sinful generation; of him
also shall the Son of man be ashamed, when he cometh
in the glory of his Father with the holy angels."
Mark 8:38
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