I have EntityB which inherits from EntityA. Can I have TableB containing fields added to class EntityB, and TableA containing fields of EntityA?

No, this feature is not supported.

We do support the following:

public class PersonBean implements javax.ejb.EntityBean {
  // this field is container managed...
  public String gender;

    ... bean methods and getter/setter methods deleted for brevity

}

public class CustomerBean extends PersonBean {

  // these fields are container managed...
  public String name;
  public String ID;

  public String address;


   ... bean methods and getter/setter methods deleted for brevity

}
It is possible to have this structure when you store all of the CMP fields for both classes in one table.