Re: Need Help in query - Mailing list pgsql-general

Thanks! I did not know such a function exists.

Hallo

This I think should work.

To get the usernames by hour as you describe:

SELECT h.hour, usrlog.userid
(select generate_series(1,24) as hour) as h
inner join
usrlog
on h.hour >= usrlog.loginhr and h.hour <= usrlog.logouthr
order by h.hour, usrlog.userid;

To get the number of users per hour :

Select h.hour, count(*) asNumberOfUsers
(select generate_series(1,24) as hour) h
inner join
usrlog
on h.hour >= usrlog.loginhr and h.hour <= usrlog.logouthr
group by h.hour;

HTH

Nicklas



2010-12-23 skrev Satish Burnwal (sburnwal) :

I need a help in writing a query. I have data as follows:
>
>mydb=# select * from usrlog ;
> logid | userid | loginhr | logouthr
>-------+----------+---------+----------
> 0 | sburnwal | 0 | 1
> 1 | rickyrs | 1 | 5
> 2 | satishbn | 1 | 6
> 3 | taohujin | 2 | 4
> 4 | jospehm | 4 | 5
>
>
>Table captures the login and logout time (taking hour here to simplify)
>of users and my aim to find the number of logged-in users (online users)
>at every hr (1st hr i.e. 0-1, 2nd hrs i.e. 1-2, 3rd hr i.e. 2-3 and ...
>so on). As the data indicates, use is not logging out in same hr as hr
>of login. A user can be logged-in for more than one hr. For example,
>here user rickyrs is logged-in for 1st, 2nd, 3rd, 4th and 5th hr. My
>query needs to find out in the last 24 hrs, how many users were
>logged-in at each hr. I want the result this way:
>
>Nth-hr user
>---------------------------
>1 sburnwal
>2 rickyrs
>2 satishbn
>3 rickyrs
>3 satishbn
>3 taohujin
>4 rickyrs
>4 satishbn
>4 taohujin
>4 josephm
>
>Appreciate your response in advance. For me, even the count of users on
>hourly basis is fine.
>
>Thanks
>-Satish
>
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