I've got a homework assignment that requires that I use Oracle 10g Express to implement an Object Relational database to track phone billing data. I have a superclass of Communications with subclasses of Call, Text, and Data. I'm hitting a snag with properly populating these tables so that I can find the appropriate data in the various tables.

My Types and Tables are declared as such:

create type CommunicationType as object (
  -- column names here
) not final;
create type CallType under CommunicationType (
  -- column names here
);
create type TextType under CommunicationType (
  -- column names here
);
create type DataType under CommunicationType (
  -- column names here
);
create table Communications of CommunicationType (
  -- Primary and Foreign key constraints here
);
create table Calls of CallType;
create table Texts of TextType;
create table Datas of DataType;

When I try to insert data into one of the subclasses, its entry doesn't appear in the superclass. Likewise if I insert into the superclass, it doesn't show up in the appropriate subclass. For example, insert into Calls values (CallType( -- Values -- )); doesn't show any data in Communications. Nor does insert into Communications values (CallType( -- Values -- )); show anything in Calls.

What am I doing wrong?