Date: Tue, 23 Aug 2005 11:12:38 +0200
From: "A. Kretschmer" <akretschmer@despammed.com>
To: pgsql-sql@postgresql.org
Subject: Re: diary constraints
Message-ID: <20050823091238.GD24431@webserv.wug-glas.de>
Mail-Followup-To: "A. Kretschmer" <akretschmer@despammed.com>,
	pgsql-sql@postgresql.org
References: <200508230933.59043.gary.stainburn@ringways.co.uk>
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am  23.08.2005, um  9:33:58 +0100 mailte Gary Stainburn folgendes:
> Hi folks
> 
> I know this has been discussed in the past, but no amount of keywords 
> has returned anything from the archives.
> 
> I want to create a courtesy car diary diary system where I have a table 
> containing all of the cortesy cars in the pool, and then an allocation 
> table which has two timestamps, one for the start date/time and one for 
> the return date/time.
> 
> How do I go about creating constraints on inserts and updates to ensure 
> that
> 
> a) the finish is after the start

with a check-constraint like this:
create table foobar (t1 timestamp, t2 timestamp check (t2>t1));


> b) two allocations for a single vehicle don't overlap.

possibly with a trigger.


Regards, Andreas
-- 
Andreas Kretschmer    (Kontakt: siehe Header)
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