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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 18:06:33
Message-ID: 7be3f35d0809251106w6dccd62fsd43ec4f53825fe4c@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-general
uuuuuups, you need to specify the table in the select, so

 select t.x,t.y,t.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)



On Thu, Sep 25, 2008 at 20:05, Harald Armin Massa
<haraldarminmassa(at)gmail(dot)com> wrote:
> 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
>>
>>
>>
>
>
>
> --
> GHUM Harald Massa
> persuadere et programmare
> Harald Armin Massa
> Spielberger Straße 49
> 70435 Stuttgart
> 0173/9409607
> no fx, no carrier pigeon
> -
> EuroPython 2009 will take place in Birmingham - Stay tuned!
>



-- 
GHUM Harald Massa
persuadere et programmare
Harald Armin Massa
Spielberger Straße 49
70435 Stuttgart
0173/9409607
no fx, no carrier pigeon
-
EuroPython 2009 will take place in Birmingham - Stay tuned!

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