Here's a ER modelling situation.
An investor can either be an individual, family or an institution.
What I have seen the way it has been modelled is that there are there
are three entity types called, INDIVIDUAL, INSTITUTION, FAMILY. Now, a
union has been created to show that the union of these three entity
types is the INVESTOR enitity type at the bottom.
I would like to know how the above implementation is different from the
implementation where we can have the INVESTOR as the superclass entity
type and then derive three sub classes entity types called INDIVIDUAL,
INSTITUTION, FAMILY.
Which one is more advantageous and under what circumstances? Are the
above two different implementations the same?
Bye
Received on Wed Feb 15 2006 - 08:08:46 CST
