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Re: Problem in age on a dates interval

From: Theodore Petrosky <tedpet5(at)yahoo(dot)com>
To: Luis Sousa <llsousa(at)ualg(dot)pt>, pgsql-sql(at)postgresql(dot)org
Subject: Re: Problem in age on a dates interval
Date: 2004-07-16 11:52:14
Message-ID: 20040716115215.29699.qmail@web41010.mail.yahoo.com (view raw or flat)
Thread:
Lists: pgsql-sql
Luis,

wow.... at first I thought I had my head around a leap
year problem so I advanced your query a year....

testbed=# SELECT age('2005-05-14
16:00'::timestamp,'2005-02-18 16:00'::timestamp);
      age       
----------------
 2 mons 24 days
(1 row)

testbed =# SELECT '2005-02-18 16:00'::timestamp +'2
mons 24 days'::interval;
      ?column?       
---------------------
 2005-05-12 16:00:00
(1 row)

I just thought I would let you know it can get
worse..... :) I don't know how daylight savings time
is playing this problem... but I didn't expect the
problem to grow like that.

Ted

--- Luis Sousa <llsousa(at)ualg(dot)pt> wrote:
> Hi all,
> 
> I'm using PostgreSQL 7.3.3 on i386-pc-linux-gnu,
> compiled by GCC gcc 
> (GCC) 3.3 (Debian), and I don't understand the
> results of the following 
> queries:
> 
> 
> SELECT age('2004-05-14 16:00'::timestamp,'2004-02-18
> 16:00'::timestamp);
>       age      
> ----------------
>  2 mons 25 days
> 
> SELECT '2004-02-18 16:00'::timestamp+'2 mons 25
> days'::interval;
>       ?column?      
> ---------------------
>  2004-05-13 16:00:00
> 
> In this case, the age from 2004-05-14 16:00 to
> 2004-02-18 16:00 is 2 
> mons 25 days, but if I add the age to the initial
> date, it returns one 
> day less!?
> 
> SELECT age('2004-05-26 16:00'::timestamp,'2004-02-18
> 16:00'::timestamp);
>       age     
> ---------------
>  3 mons 8 days
> 
> SELECT '2004-02-18 16:00'::timestamp+'3 mons 8
> days'::interval;
>       ?column?      
> ---------------------
>  2004-05-26 16:00:00
> 
> Here, the age between 2004-05-26 16:00 and
> 2004-02-18 16:00 is 3 mons 8 
> days, and this interval added to the initial date
> gives the correct result!!
> 



		
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Subject: Re: Problem in age on a dates interval
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