Message-ID: <43833B3D.2020407@hardgeus.com>
Date: Tue, 22 Nov 2005 09:37:33 -0600
From: John McCawley <nospam@hardgeus.com>
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To: Joost Kraaijeveld <J.Kraaijeveld@Askesis.nl>
Cc: "Pgsql-sql@postgresql.org" <Pgsql-sql@postgresql.org>
Subject: Re: Foreign key to 2 tables problem
References: <1132673053.5701.9.camel@Panoramix>
In-Reply-To: <1132673053.5701.9.camel@Panoramix>
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I've never seen anything like that.  I'm sure it's conceivable that you 
could write a weird trigger for it, but you have to consider 
maintainability, and what your queries are going to look like.  I 
haven't seen your datamodel, but it would seem that you could accomplish 
what you're looking for by having two separate foriegn key columns in 
the bankaccount table, one for the customer and one for the supplier.  
While your queries may end up somewhat funky, I can't imagine they'd be 
any worse than what would occur with what you're suggesting.

However, if customers or suppliers can have multiple accounts, you are 
going to need an intermediate table, as suggested by Neil.


Joost Kraaijeveld wrote:

>Hi,
>
>Is there a way to create a foreign key to 2 tables: e.g. a bankaccount
>table that has a column "owner", that must point to a record in either
>the customer or the supplier table?
>
>
>TIA
>
>  
>