Re: how to get a number of seconds in some interval ?

Scott Marlowe wrote:

> True.  But that's only because it doesn't have a date to work against.
>  If you run:
> 
> select '2007-02-01 12:00:00'::timestamp + '1 month'::interval;
> you get: 2007-03-01 12:00:00
> 
> If you run:
> select '2007-03-01 12:00:00'::timestamp + '1 month'::interval;
> you get:  2007-04-01 12:00:00
> 
> Then, if we run:
>  select ('2007-03-01 12:00:00'::timestamp + '1 month'::interval) -
> '2007-03-01 12:00:00'::timestamp;
> we get: 31 days
> 
> But if we run:
>  select ('2007-02-01 12:00:00'::timestamp + '1 month'::interval) -
> '2007-02-01 12:00:00'::timestamp;
> we get: 28 days
> 
> So, I'm not sure how many days a month has.

Try looking at a calendar.;-)

You will find that these are the exact days between the two dates. Feb 
has 28 days, so 1st of feb plus 1 month puts you at 1st of march

march has 31 days so 1st of march plus 1 month puts you at 1st of april.

Try a leap year -

select ('2008-02-01 12:00:00'::timestamp + '1 month'::interval) - 
'2008-02-01 12:00:00'::timestamp;
  ?column?
----------
  29 days
(1 row)


-- 

Shane Ambler
pgSQL (at) Sheeky (dot) Biz

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