Need magical advice for counting NOTHING

Поиск
Список
Период
Сортировка
От Andreas
Тема Need magical advice for counting NOTHING
Дата
Msg-id 4A67EEB2.1070302@gmx.net
обсуждение исходный текст
Ответы Re: Need magical advice for counting NOTHING  (Shane Ambler <pgsql@Sheeky.Biz>)
Re: Need magical advice for counting NOTHING  ("A. Kretschmer" <andreas.kretschmer@schollglas.com>)
Re: Need magical advice for counting NOTHING  (Glenn Maynard <glenn@zewt.org>)
Список pgsql-sql
Hi,
The source select counts log-events per user.
All is well when a user has at least one event per log_type in the log 
within a given timespan.
If one log_type is missing COUNT() has nothing to count and there is 
expectedly no result line that says 0.
BUT I need this 0-line because of a crosstab.  :(
I need to know how to prevent in my crosstab categories on the right to 
slip to the left, when the left category is emptyy.

Server 8.3.5

3 tables
log  (log_id, log_type_fk, user_fk, ts timestamp, ...)
users  (user_id, user_name, ...)
log_type  (log_type_id, log_type)
There are 3 events as log_type.

I naively tried
SELECT user_name, log_type_fk, COUNT(log_type_fk)
FROM log
JOIN users ON (user_id = user_fk)
WHERE (ts IS BETWEEN  sometime  AND   another)
GROUP BY user_name, log_type_fk
ORDER BY user_name, log_type_fk

This results e.g. to

user1, type1, 2
user1, type2, 3
user1, type3, 7
user2, type1, 11
user2, type3, 17

but I needed also
user2, type2, 0

How would I get there ?

Regards
Andreas


В списке pgsql-sql по дате отправления:

Предыдущее
От: nha
Дата:
Сообщение: Re: how to tell if column set on update
Следующее
От: Glenn Maynard
Дата:
Сообщение: Bit by "commands ignored until end of transaction block" again