Re: work hour calculations

2007/9/9, novice <user(dot)postgresql(at)gmail(dot)com>:
> > > > The result I'm expecting for the above to be
> > > >
> > > > notification_time | finished_time | actual
> > > > ------------------------+------------------------+-----------------
> > > > 2007-07-06 15:50:00+10 | 2007-07-09 07:10:00+10 | 01:20:00
> > > > 2007-07-07 12:30:00+10 | 2007-07-09 07:20:00+10 | 00:20:00
> >
>
> create table log
> (
> id integer PRIMARY KEY,
> notification_time timestamp with time zone,
> finished_time timestamp with time zone
> );
>
> INSERT INTO log values (1, '2007-07-06 15:50', '2007-07-09 07:10');
> INSERT INTO log values (2, '2007-07-07 12:30', '2007-07-09 07:20');
>
> SELECT notification_time, finished_time, sum(finished_time -
> notification_time) as actual
> FROM log
> GROUP BY notification_time, finished_time;
>

OK. so I have bad news for you: with such structure, you will have to
write some function to calculate work time spent for each task.

general algorithm would be similar to

* take the notification time
* take the finished_time
* set pointer := notif. time
* set actual := 0
* while there is any weekend between the pointer and finished_time,
do the following
** set actual := actual + ( weekend begin - pointer )
** move pointer to the next monday morning
* set actual := actual + ( finished_time - pointer )

BUT:
this is ugly.
do you always assume that people are doing ONLY one task at a time?

maybe think of representing work sheets in the database?

maybe think of adding "work_time" field to your table (why not trust
people, they know best)

maybe the application you use for entering data could give some "hint"
basing on above algo.

good luck,

--
Filip Rembiałkowski