Re: One-To-One Relationships

From: JOG <>
Date: Fri, 30 Nov 2007 10:33:49 -0800 (PST)
Message-ID: <>

On Nov 30, 6:03 pm, Tegiri Nenashi <> wrote:
> On Nov 30, 8:19 am, Jan Hidders <> wrote:
> The distinction between entities /
> > relationships, domain objects / predicates is pretty well-established
> > in linguistics, philosophy and logic.
> That certainly means you can define them formally in database terms,
> right?
> Here is one such attempt:
> It defines an entity as a relation (aka table:-) with a single
> noncomposite key, and relationship as a table with composite key. Does
> this definition pretty much exhausts the entity-relationship theory?

I like the insight that both 'entities' and 'relationships' are subtypes of a parent concept, that is simply a set of attributes and values. I'd like to see a formalization of that which doesn't rely on relational theory and the concept of keys however, even though I imagine there would be a direct correspondence.

> (But then BB remark was that order line is a weak entity).
Received on Fri Nov 30 2007 - 19:33:49 CET

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