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From: Richard Huxton <dev@archonet.com>
Organization: Archonet Ltd
To: "David Loh" <david@bizsurf.com>, <pgsql-sql@postgresql.org>
Subject: Re: A minute in timestamp
Date: Thu, 8 May 2003 08:24:03 +0100
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On Thursday 08 May 2003 7:40 am, David Loh wrote:
> Hi all.
> After some read of postgres' documentations, I can't found any command
> perform similar task like timediff() in other SQL server, the only thing I
> got is date_part(). For my case, what I actually need is to create a
> trigger (before insert) that check previous record (1 mins), grab the
> previous value and deduct new value (NEW.myValue :=3D Previous.myValue -
> NEW.myOtherValue), and since the records are insert every minutes,the
> function should trace back to the record entered a minute ago (for e.g,
> 12:38 will check for record of 12:37 and grab the value), hence timestamp
> even include the milli-second, is there any command/trick to check if the
> record are entered approximately 55-65 secs (1 minutes +/- 5 secs) ?=20

Do exactly as you've just described:

SELECT ....
WHERE t BETWEEN now()-'1 min 5 secs'::interval AND now()-'55 secs'::interval

It takes a while to get used to PG's date/time/interval types vs timediff()=
=20
functions you get in most systems. I find them clearer now I've got used to=
=20
them.

--=20
  Richard Huxton