Re: No Documentation for to_char(INTERVAL, mask)

On Tue, Mar 06, 2001 at 09:22:25AM -0800, Josh Berkus wrote:
> Karel,
> 
> >  The 'interval' version of to_char() isn't implemented -- may be in 7.2
> > (it's high in my TODO list:-)
> 
>     Grazie.  (One of the things I love about PostgreSQL is being able to
> get definitive answers on functionality -- try asking Microsoft an "is
> this implemented?" question!)

:-)

>     Given the lack of to_char(interval), I'd like to write a PLPGSQL
> function to fill the gap in the meantime.  If you can answer a few
> questions about how interval values work, it would be immensely helpful:
> 
> 1. Hours, minutes, and seconds are displayed as "00:00:00".  Days are
> displayed as "0 00:00:00".  How are weeks, months, and years displayed?
> 
> 2. If months have their own placeholder in the Interval data type, how
> many days make up a month?  Is it a fixed value, or does it depend on
> the calendar?
A displayed format is external string alternate of a internal number based
form. A interval/timestamp string that you use in SQL is parsed to 'tm'
struct (see man ctime) where has each item like hours, minutes own field.
For some date/time operation is used Julian date (..etc) -- internaly PG
not works with strings for date/time.
 I mean is too much difficult write a 'interval' to_char() version in 
some procedural language without access to real (internal) form of 
'interval'. 
Big date/time guru is Thomas (CC:), comments?
    Karel

-- Karel Zak  <zakkr@zf.jcu.cz>http://home.zf.jcu.cz/~zakkr/C, PostgreSQL, PHP, WWW, http://docs.linux.cz,
http://mape.jcu.cz