Inheritance mapping to table

Question

Hello,
I am trying to create a project in Toplink with the following classes (getters and setters ommited):
class GenericPerson {
int id;
String email;
Vector phoneNumbers;
class Employee extends GenericPerson {
String name;
Date birthday;
class Enterprise extends GenericPerson {
String enterpriseName;
int cnpj;
class PhoneNumber {
int id;
int areaCode;
String number;
GenericPerson contact;
In my model, the PhoneNumber can be mapped to an Employee or to an Enterprise, so I map it to the superclass.
But my superclass is not mapped to a table, I chose to map the inherited attributes to the leaf classes.
So, how can I map the attribute "contact" in the class PhoneNumber to a database field? I think I am having a conceptual problem here...
[]s

Answer 1

Impedence mismatch...
What would you like the schema to look like? What you're looking for is to have a foreign key in PHONE_NUMBER table that points to EITHER the ENTERPRISE or EMPLOYEE table... Any DBA will have a heart attack if you suggest to have a FK that points to one of 2 tables... So, you need to consider having an association table for each relationship and mapping as a M-M (it's still a 1-M in your java model, but M-M in the mapping by virtue of having a relationship table to store it), then you don't need the back reference... Or, you can map the root table.
My recommendation is to create relation tables and use M-M mapping.
- Don