Date: Tue, 20 May 2003 09:57:26 -0700 (PDT)
From: Stephan Szabo <sszabo@megazone23.bigpanda.com>
To: Jan Bodey <jan_bodey@hotmail.com>
Cc: <pgsql-sql@postgresql.org>
Subject: Re: Date comparison question
In-Reply-To: <Law11-F4684J5kbuOAb0001655b@hotmail.com>
Message-ID: <20030520095059.Q68048-100000@megazone23.bigpanda.com>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII

On Tue, 20 May 2003, Jan Bodey wrote:

> Hi
>
> I require a query that will see if a stored date is more than a certain
> interval before the current date.  Using an interval of 10 hours, the query
> would be something like:
>
> SELECT * FROM utable
> WHERE now() - utimestamp > interval '10 hours';
>
> The problem I am having is that the interval is not fixed, and I would like
> to be able to store it as a value in a database table.  The unit of the
> interval can, however, be fixed, and will almost certainly be fixed to
> hours.
>
> I have not been able to find a way of doing what I require, does anybody
> have any ideas to what I need to do?

If you assume that you're just going to stick one row in the interval
table, I think you can do something kinda like:

 create table interv(i interval);
 insert into interv values ('10 hours');
 analyze interv;
 select utable.* from utable, interv
  where now()-utimestamp>i;

This could be made more complicated if you want to have multiple interval
values, etc.  Also, neither of the above is probably terribly fast if
utable is big.