Re: April 1

Thanks,

I have no Idea how this question was posted again.  I certainly did not
repost this question.


----- Original Message -----
From: "Martijn van Oosterhout" <kleptog@svana.org>
To: "Andrew Bartley" <abartley@evolvosystems.com>
Cc: <pgsql-general@postgresql.org>
Sent: Friday, March 08, 2002 9:32 AM
Subject: Re: [GENERAL] April 1


> On Mon, Mar 04, 2002 at 09:57:56AM +1100, Andrew Bartley wrote:
> >
> > Hi
> >
> > I'm having trouble calculating a date of April 1 2002.
> >
> > Postgres 7.1.3 Linux 2.4.14
> >
> > select date(date('2002-03-30') + interval('1 day'))
> >
> > result 2002-03-31
> >
> > select date(date('2002-03-31') + interval('1 day'))
> >
> > result 2002-03-31
> >
> > It seems as though the "+ interval('1 day'))" only adds 23 hours rather
than 24.
> >
> > So adding "interval( '1 day')" to the march 31 returns march 31.
> >
> > It may have something to do with day light savings.
> >
> > Can any one suggest a work around?
> >
> > Is this a bug?
>
> Someone actually answered this on this list not so long ago. Your problem
is
> that due to daylight savings, March 31 is actually 25 hours long, not 24.
> Your use of interval promotes the date to a datetime, adds 24 hours and
> truncates back to a date leaving you with the same date.
>
> Two solutions:
>
> 1. Don't use interval.
>
> # select date('2002-03-31') + 1;
> result 2002-04-01
>
> 2. Add 28 hours instead
> # select date(date('2002-03-31') + interval('28 hours'))
> result 2002-04-01
>
> HTH,
> --
> Martijn van Oosterhout <kleptog@svana.org>
> http://svana.org/kleptog/
> > If the company that invents a cure for AIDS is expected to make their
> > money back in 17 years, why can't we ask the same of the company that
> > markets big-titted lip-syncing chicks and goddamn cartoon mice?
>
>