On Thu, Jul 2, 2009 at 3:48 PM, Jasmin
Dizdarevic<jasmin(dot)dizdarevic(at)gmail(dot)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