Re: Pizza Example

"Tony" <andrewst_at_onetel.net.uk> wrote in message news:c0e3f26e.0404070340.b1b913e_at_posting.google.com...
> Whether that means the pizza and its toppings form a single real-world
> object is another matter. If using a MV attribute for toppings means
> that the pizza and its toppings constitute a single real-world object,
> does that mean that a MV attribute "children" in an employee record
> means that the employee and all his children constitute a single
> real-world object also?

That's a very good point. This is entity-relationship modeling gone haywire; the boundary between an entity and a relationship is often not clear-cut, and even when it is, modeling them differently gives no additional traction. Date gives the example of marriages - a marriage is a relationship between 2 entities (with additional constraints on gender, if certain politicians have their way), but viewed from the point of view of a diocesan or church database, each marriage is an entity with attributes of its own. So "entity" ends up meaning very little. It's predicates and propositions. Received on Wed Apr 07 2004 - 14:33:04 CEST