Re: Determining period between 2 dates

On 02/16/2011 09:07 AM, Marti Raudsepp wrote:
> On Wed, Feb 16, 2011 at 18:03, Thom Brown<thom@linux.com>  wrote:
>> For the number of fortnights, that becomes:
>>
>> select extract(epoch from now() - '2010-01-01 11:45:13'::timestamp)/60/60/24/14;
>>
>> You'd think with PostgreSQL having such a rich type system, it
>> wouldn't need to come to that.  It's just asking for the number of
>> intervals between 2 timestamps rather than the number of seconds and
>> dividing it to the point you get your answer.
> I think a good generic solution would be an interval/interval operator
> that returns numeric. Then the above becomes:
>
> SELECT (now() - timestamp '2010-01-01 11:45:13') / interval '2 weeks';
>
> However, looking at the code, it's not so obvious what to do if the
> intervals contain months.
>
> Regards,
> Marti
>
Actually, what I would really like is an option in the to_char format 
that would display an interval using an arbitrary combination of units. 
For instance, right now I can display parts of an interval:

steve=# select to_char('10d 11h 21m 3s'::interval, 'DD'); to_char
--------- 10

steve=# select to_char('10d 11h 21m 3s'::interval, 'SS'); to_char
--------- 03

steve=# select to_char('10d 11h 21m 3s'::interval, 'MI'); to_char
--------- 21

But those formats extract portions of the interval. I would like to be 
able to display the *entire* interval filling the largest portions first 
and continuing to smaller units, say:

select to_char('10d 11h 21m 3s'::interval, 'XM SS');
to_char
--------
904863

or

select to_char('10d 11h 21m 3s'::interval, 'XM MI:SS');
to_char
--------
15081:03

And as long as I'm on the subject, decimal time display would be handy 
as well (especially decimal hours and minutes).

The use case is anything that accumulates time - especially for billing 
purposes: 2.4 hours for the attorney, 11434.8 minutes of long-distance 
this month, etc.

I can write these myself, of course, but built-in would be nice.

-Steve