Re: inverted foreign key constraint

From: Matthew Fuller <matthewlf_at_my-deja.com>
Date: Fri, 19 Jan 2001 13:25:12 GMT
Message-ID: <949f7j$ahb$1@nnrp1.deja.com>

In article <3A674A81.A982EF8A_at_P.NL>,
Joporus <C_at_P.NL> wrote:
>
> Hi
>
> I am trying to define a constraint in order to exclude something , in
> this case an articlenumber, which is stored in one table, also to
exist
> in an other table. Something like an inverted foreign key, I would
say.
>
> I tried it with a 'check' constraint, but that didn't allow a subquery
> on the other table.
>
> Anybody got a tip?
>
> Arjen
>
>

Arjen,

The only way that I know of to do this is in a trigger that checks for the value in the other table. This may or may not be possible/reliable depending on how static your data is.

Matt.

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http://www.deja.com/ Received on Fri Jan 19 2001 - 07:25:12 CST