Re: diary constraints

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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