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Re: How to select rows that are the max for each subcategory?

From: "Harald Armin Massa" <haraldarminmassa(at)gmail(dot)com>
To: "Kynn Jones" <kynnjo(at)gmail(dot)com>
Cc: "pgsql-general General" <pgsql-general(at)postgresql(dot)org>
Subject: Re: How to select rows that are the max for each subcategory?
Date: 2008-09-25 18:05:49
Message-ID: 7be3f35d0809251105v453e46a3g423f16aae6be59a8@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-general
select x,y,z
from
t join (select x, max(y) as my from t group by x) t1 on (t.x=t1.x and t.y=t1.my)

best wishes

Harald

On Thu, Sep 25, 2008 at 20:01, Kynn Jones <kynnjo(at)gmail(dot)com> wrote:
> Suppose I have a table T that has, among its columns, the fields X and Y,
> where Y is an integer, and multiple rows with the same value of X are
> possible.  I want to select the rows corresponding to the greatest values of
> Y for each value of X.  E.g. suppose that T is
> X Y Z
> a  1 eenie
> a  3 meenie
> a  2 miny
> b  4 moe
> b  0 catch
> ...the result of the desired query would be
> a  3 meenie
> b  4 moe
> TIA!
> Kynnjo
>
>
>



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