Re: I need a SQL... - Mailing list pgsql-general

When i run it, it works as intended (on pg 7.3.3). Which version do you use?

Are you absolutely sure you copied it exactly? You typed in '>=' and not '=', right?

/Mattias

----- Original Message -----
From: "Bjørn T Johansen" <btj@havleik.no>
To: "Mattias Kregert" <mattias@kregert.se>
Cc: <pgsql-general@postgresql.org>
Sent: Thursday, September 11, 2003 3:02 PM
Subject: Re: [GENERAL] I need a SQL...


> Well, it's close... :)
>
> But it looks like the case doesn't work..
> If I run your sql, the timediff is negative.
>
> But if I run this:
> SELECT (stoptime-starttime+'24 hours') as timediff FROM mytable
> the timediff has correct value..
>
> Do you see any error in the case, cause I don't?
>
>
> BTJ
>
> On Thu, 2003-09-11 at 14:29, Mattias Kregert wrote:
> > Solution:
> >
> > SELECT starttime, stoptime, (CASE WHEN stoptime-starttime >= 0 THEN
> > stoptime-starttime ELSE stoptime-starttime+'24 hours' END) as timediff
> > FROM mytable;
> >
> > /Mattias
> >
> >         ----- Original Message -----
> >         From: Bjørn T Johansen
> >         To: Andrew L. Gould
> >         Cc: PostgreSQL general list
> >         Sent: Thursday, September 11, 2003 2:12 PM
> >         Subject: Re: [GENERAL] I need a SQL...
> >
> >         On Thu, 2003-09-11 at 14:07, Andrew L. Gould wrote:
> >         > On Thursday 11 September 2003 06:25 am, Bjørn T Johansen wrote:
> >         > > I need to write a SQL that calculates the interval between a start time
> >         > > and a stop time. This is the easy part. The problem is that I only have
> >         > > the time part, i.e. no date, so how can I be sure to also calculate the
> >         > > interval if the start time is before midnight and the stop time is after
> >         > > midnight?
> >         > >
> >         > >
> >         > > Regards,
> >         > >
> >         > > BTJ
> >         >
> >         > If the activity or period you are measuring can equal or exceed 12 hours, you
> >         > won't be able to calculate it reliably without a start date and a stop date.
> >         > If the periods are always less than 12 hours (and you assume all the data is
> >         > good), then stop times that are less than start times would indicate an
> >         > intervening midnight.
> >         >
> >         > The dates do not have to be in the same fields as the times, since you can add
> >         > date and time data to create a timestamp for datetime calculations:
> >         >
> >         > (stop_date + stop_time) - (start_date + start_time)
> >         >
> >         > Best of luck,
> >         >
> >         > Andrew Gould
> >
> >
> >
> >         Yes, the period can exceed 12 hours, so what you are saying is that this is not possible to solve
> >         without the date part? I can write this logic in my business logic but I was hoping to
> >         solve this in my database layer...
> >
> >
> >         BTJ
>
>
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