I'd code it more general to allow for any user type:
select
yw, substr(id,1,2) as user_type, count(1)
from
pref_money
group by
yw, user_type
You can use some clever pivoting to get the user_types to be columns, but I see no need to waste db cycles.
You can get the report you want by one-pass processing of the above result set.
If you have mountains of data I'd precompute, before insert or during insert by a trigger, the user_type and store it
separately.
Kiriakos
http://www.mockbites.com
On Feb 22, 2012, at 3:36 PM, Alexander Farber wrote:
> Hello,
>
> I have a table holding week numbers (as strings)
> and user ids starting with OK, VK, FB, GG, MR, DE
> (coming through diff. soc. networks to my site):
>
> afarber@www:~> psql
> psql (8.4.9)
> Type "help" for help.
>
> pref=> select * from pref_money;
>
> id | money | yw
> -------------------------+--------+---------
> OK19644992852 | 8 | 2010-44
> OK21807961329 | 114 | 2010-44
> FB1845091917 | 774 | 2010-44
> OK172682607383 | -34 | 2010-44
> VK14831014 | 14 | 2010-44
> VK91770810 | 2368 | 2010-44
> DE8341 | 795 | 2010-44
> VK99736508 | 97 | 2010-44
>
> I'm trying to count those different users.
>
> For one type of users (here Facebook) it's easy:
>
>
> pref=> select yw, count(*) from pref_money
> where id like 'FB%' group by yw order by yw desc;
>
> yw | count
> ---------+-------
> 2012-08 | 32
> 2012-07 | 32
> 2012-06 | 37
> 2012-05 | 46
> 2012-04 | 41
>
> But if I want to have a table displaying all users
> (a column for "FB%", a column for "OK%", etc.) -
> then I either have to perform a lot of copy-paste and
> vim-editing or maybe someone can give me an advice?
>
> I've reread the having-doc at
> http://www.postgresql.org/docs/8.4/static/tutorial-agg.html
> and still can't figure it out...
>
> Thank you
> Alex
>
> --
> Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-general