From: Greg Stark <gsstark@mit.edu>
To: Jasmin Dizdarevic <jasmin.dizdarevic@gmail.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: Create custom aggregate function and custom sfunc
Date: Thu, 2 Jul 2009 22:21:01 +0100
Message-ID: <407d949e0907021421qb1df8b1o9468f343298f08dd@mail.gmail.com> (raw)
In-Reply-To: <a0eee4d40907020748p7cb9bad7mad8817e60e9ea89@mail.gmail.com>
References: <a0eee4d40907020748p7cb9bad7mad8817e60e9ea89@mail.gmail.com>
On Thu, Jul 2, 2009 at 3:48 PM, Jasmin
Dizdarevic<jasmin.dizdarevic@gmail.com> wrote:
> customer ; seg
> 111 ; L1
> 111 ; L2
> 111 ; L1
> 222 ; L3
> 222 ; L3
> 222 ; L2
>
> the result should look like this:
>
> 111: L1 - because L1 is higher than L2 and ratio of L1 : L2 is 2 : 1
> 222: L3 - because L3 is higher than L2 and ratio of L3 : L2 is 2 : 1
Are you just looking for the most frequent seg for each customer?
select distinct on (customer) customer,seg
from (select customer, seg, count(*) as n from tab group by seg)
order by customer, n desc
That doesn't give the ratios though.
--
greg
http://mit.edu/~gsstark/resume.pdf
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To: pgsql-sql@postgresql.org
Cc: gsstark@mit.edu, jasmin.dizdarevic@gmail.com
Subject: Re: Create custom aggregate function and custom sfunc
In-Reply-To: <407d949e0907021421qb1df8b1o9468f343298f08dd@mail.gmail.com>
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