From: Shane Ambler <pgsql@Sheeky.Biz>
To: Scott Marlowe <scott.marlowe@gmail.com>
Cc: Achilleas Mantzios <achill@matrix.gatewaynet.com>
Cc: pgsql-admin@postgresql.org, Tom Lane <tgl@sss.pgh.pa.us>
Cc: Julius Tuskenis <julius@nsoft.lt>
Subject: Re: how to get a number of seconds in some interval ?
Date: Tue, 13 May 2008 18:12:41 +0930
Message-ID: <48295481.50800@Sheeky.Biz> (raw)
In-Reply-To: <dcc563d10805130122s7ef074bfra86ee43978c5c65f@mail.gmail.com>
References: <482849B0.6050103@nsoft.lt>
<200805121801.35101.achill@matrix.gatewaynet.com>
<20080.1210604951@sss.pgh.pa.us>
<200805130956.51872.achill@matrix.gatewaynet.com>
<dcc563d10805130122s7ef074bfra86ee43978c5c65f@mail.gmail.com>
Scott Marlowe wrote:
> True. But that's only because it doesn't have a date to work against.
> If you run:
>
> select '2007-02-01 12:00:00'::timestamp + '1 month'::interval;
> you get: 2007-03-01 12:00:00
>
> If you run:
> select '2007-03-01 12:00:00'::timestamp + '1 month'::interval;
> you get: 2007-04-01 12:00:00
>
> Then, if we run:
> select ('2007-03-01 12:00:00'::timestamp + '1 month'::interval) -
> '2007-03-01 12:00:00'::timestamp;
> we get: 31 days
>
> But if we run:
> select ('2007-02-01 12:00:00'::timestamp + '1 month'::interval) -
> '2007-02-01 12:00:00'::timestamp;
> we get: 28 days
>
> So, I'm not sure how many days a month has.
Try looking at a calendar.;-)
You will find that these are the exact days between the two dates. Feb
has 28 days, so 1st of feb plus 1 month puts you at 1st of march
march has 31 days so 1st of march plus 1 month puts you at 1st of april.
Try a leap year -
select ('2008-02-01 12:00:00'::timestamp + '1 month'::interval) -
'2008-02-01 12:00:00'::timestamp;
?column?
----------
29 days
(1 row)
--
Shane Ambler
pgSQL (at) Sheeky (dot) Biz
Get Sheeky @ http://Sheeky.Biz
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Cc: pgsql@Sheeky.Biz, scott.marlowe@gmail.com, achill@matrix.gatewaynet.com, tgl@sss.pgh.pa.us, julius@nsoft.lt
Subject: Re: how to get a number of seconds in some interval ?
In-Reply-To: <48295481.50800@Sheeky.Biz>
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