Re: average/stddev on all values returned by a select distinct - Mailing list pgsql-general

Michael Fuhr wrote:
> On Tue, Jul 17, 2007 at 01:51:21PM +0100, ann hedley wrote:
>
>> What I want is the average and stddev of the set of lengths returned by
>> this query.  Something like...
>>
>> select average(select distinct on (id) length(consensus) from cluster
>> order by id,length(consensus) desc);
>>
>
> I think this is what you're looking for:
>
> select avg(length)
>   from (
>     select distinct on (id) length(consensus)
>       from cluster
>      order by id, length(consensus) desc
>   ) s;
>
>
Thank you, it was indeed.

--
Ann

"In a world without walls and fences - who needs Windows and Gates ?"
                                                           (unknown)