Re: Designer2000 & Relationship Cardinality

Oracle can enforce some cardinalities but not others.

Imagine you have two entities/tables PARENT and CHILD

You can enforce (using primary and foreign keys)

each CHILD must have one and only one PARENT each CHILD may have one and only one PARENT each PARENT may have one and only one CHILD each PARENT may have one or more CHILDs

Using Foreign Keys/Primary Keys you cannot Force a PARENT to have a CHILD.
Have numbered cardinalities
(e.g. Each PARENT may have up to 3 CHILDs but no more).

You have to write bespoke code to do this kind of thing.

Simon Hedges
Gloucester
UK Received on Thu Jul 08 1999 - 20:58:57 CEST