Обсуждение: conditional aggregates
regards
mk
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.mk@gmail.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 >
regards
mk
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.mk@gmail.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
>
something like ?
Select min (case when X > 0 then X end)
HTH,
Marc Mamin
From: pgsql-sql-owner@postgresql.org [mailto:pgsql-sql-owner@postgresql.org] On Behalf Of Marcin Krawczyk
Sent: Mittwoch, 8. Dezember 2010 14:20
To: Pavel Stehule
Cc: pgsql-sql@postgresql.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.stehule@gmail.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.mk@gmail.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
>
pozdrowienia
mk
something like ?
Select min (case when X > 0 then X end)
HTH,
Marc Mamin
From: pgsql-sql-owner@postgresql.org [mailto:pgsql-sql-owner@postgresql.org] On Behalf Of Marcin Krawczyk
Sent: Mittwoch, 8. Dezember 2010 14:20
To: Pavel Stehule
Cc: pgsql-sql@postgresql.org
Subject: Re: [SQL] conditional aggregates
Yeah I know but I'm having problems creating sfunc fuction for the aggregate.
regards
mk2010/12/8 Pavel Stehule <pavel.stehule@gmail.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.mk@gmail.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
>