Re: conditional aggregates

something like ?

Select min (case when X > 0 then X end)

HTH,

Marc Mamin

From: pgsql-sql-owner(at)postgresql(dot)org
[mailto:pgsql-sql-owner(at)postgresql(dot)org] On Behalf Of Marcin Krawczyk
Sent: Mittwoch, 8. Dezember 2010 14:20
To: Pavel Stehule
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: [SQL] conditional aggregates

Yeah I know but I'm having problems creating sfunc fuction for the
aggregate.

regards
mk

2010/12/8 Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>

Hello

use a CASE statement

http://www.postgresql.org/docs/7.4/static/functions-conditional.html

Regards

Pavel Stehule

2010/12/8 Marcin Krawczyk <jankes(dot)mk(at)gmail(dot)com>:

> Hi list,
> Can anyone advise me on creating an aggregate that would take
additional
> parameter as a condition ? For example, say I have a table like this
> id;value
> 1;45
> 2;13
> 3;0
> 4;90
> I'd like to do something like this
> SELECT min_some_cond_aggregate(value,0) FROM table
> to get the minimal value from table greater than 0, in this case 13.
> I can't do SELECT min(value) FROM table WHERE value > 0 as this will
mess my
> other computations. My current solution involves a function operating
on the
> output of array_accum from the docs, but I'm looking for more elegant
> solution.
> Is this possible at all ? I'm running 8.1.
>
> regards
> mk
>