Message-Id: <6.0.2.0.0.20041024224504.03b5c7c8@localhost>
Date: Sun, 24 Oct 2004 22:54:33 -0400
To: pgsql-sql@postgresql.org
From: Larry Lennhoff <llennhoff-postgres@pexicom.com>
Subject: Create interval using column value?
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Hi

I have a table (A) with a integer column called build_interval, which 
contains the number of milliseconds betweeen builds.  I have another table 
(B) with a timestamp with timezone column called built_on.  The two tables 
share a column called join_col.  What I want to do is find all the rows in 
A which were built before now() - build_interval seconds ago.  If I could 
just write this in SQL it would look something like:

SELECT A.id FROM A JOIN B ON (join_col) WHERE built_on < now() - interval 
'build_interval seconds';  This does not work at all - I cannot find a way 
to build an interval using a column - casting an integer as an interval is 
forbidden. Can anyone suggest a way to achieve my desired result? I'm not 
wedded to the interval approach.  I can probably change the column type of 
build_interval if necessary.

I am using postgres 7.3.4

Thanks in advance for any help.