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 ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
