Re: inverse of "day of year" - Mailing list pgsql-sql

From Dana Hudes
Subject Re: inverse of "day of year"
Date
Msg-id Pine.LNX.4.58.0403221053390.12040@screamer.tcp-ip.info
Whole thread Raw
In response to Re: inverse of "day of year"  (Bruno Wolff III <bruno@wolff.to>)
Responses Re: inverse of "day of year"
List pgsql-sql
If you have the option to handle the date manipulation in Perl
use the DateTime modules. Also see Date::Calc.
A considerable amount of effort has been expended dealing with all
the nitty-gritty of time manipulation.
Use those modules , get your new date or time interval and
feed that to the dbms with a straightforward inequality .
Don't try to do date arithmetic in sql if you can avoid it you'll
run afoul of something or other.

On Mon, 22 Mar 2004, Bruno Wolff III wrote:

> On Mon, Mar 22, 2004 at 10:14:40 -0300,
>   Martin Marques <martin@bugs.unl.edu.ar> wrote:
> > 
> > Any thoughts on how this could affect date manipulation?
> 
> This is consistant with what I explained about the behavior when adding
> a month results in a day in a month past the end of the new month.
> What do you expect to have happen here?
> 
> > mydb=> select '29/2/2004'::date + ((2005 - date_part('year', now())::int) || 
> > 'years')::interval;
> >       ?column?
> > ---------------------
> >  2005-02-28 00:00:00
> > 
> > AFAIKS with other dates this works OK. :-)
> 
> The real issue with intervals is that how they work in unusual cases is
> not documented. The behavior could change in a future version without
> much fanfare.
> 
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