Re: Help with date math

Chris Hoover wrote:
> I need some help.  I am trying to replicate a function from Sybase
> ASA, and am having difficulty.
>
> I need to be able to subtract 2 date (or timestamps) and return the
> results expressed in days, weeks, month, quarters, or years.  How do I
> do this?
>
> I believe Postgres is returning the number of days when you subtract
> to days.
> i.e. postgres=# select current_date - '2007/01/01';
>  ?column?
> ----------
>       200
> (1 row)
>
>
>
> However, I can not figure out how to get the results expressed as 7
> months, or 2 quarters, x weeks, or 0 years.  I have tried to use
> date_part, but since the subtraction is returning an integer, it is
> not happy.
>
> Any help would be greatly appreciated.
>
> Chris
>
> P.S.
>
> I'm trying to replicate Sybase's datediff function.
postgres=# select age(current_date,'2007/01/01');
      age
----------------
 6 mons 20 days
(1 row)


http://www.postgresql.org/docs/8.2/static/functions-datetime.html