Re: Interval subtracting

On Saturday 18 February 2006 15:24, Milen A. Radev wrote:
> Milorad Poluga написа:
> > Hi all,
> >
> > Is there something incorrect in the above query ?
> > SELECT '10 years 1 mons 1 days'::interval - '9 years 10 mons 15 days'::interval
> >
> > ?column?
> > ---------------
> > 3 mons -14 days
> >
> > Why not '2 mons 16 days' ?
> >
> > /version = PostgreSQL 8.0.4 on i686-pc-linux-gnu, compiled by GCC gcc (GCC) 3.4.2 20041017 (Red Hat 3.4.2-6.fc3) /
>
>
> How many days are there in a month?
>

I beleive that a month is calculated on the 30-days base.

One way to solve this problem is to use a neutal date element and make timestamps :

SELECT age(('1990-01-01'::date + '10 years 1 mons 1 days'::interval)::timestamp ,
('1990-01-01'::date + '9 years 10 mons 15 days'::interval)::timestamp)

age
--------------
2 mons 16 days

Regards,
Milorad Poluga

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milorad(dot)poluga(at)cores(dot)co(dot)yu
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