Hi Tom:

I have a couple of questions related to Object Relational Features of Oracle.

I have following structures:

CREATE TYPE address_typ AS OBJECT
(line1 VARCHAR2(20), city VARCHAR2(20), COUNTRY VARCHAR2(20));

CREATE TYPE phone_typ AS OBJECT (area_cd VARCHAR2(10), phone# VARCHAR2(10));

CREATE TYPE phone_list_typ AS TABLE OF phone_typ;

CREATE TYPE person_typ AS OBJECT
(lname VARCHAR2(20), fname VARCHAR2(20),
address address_typ,
phones phone_list_typ) NOT FINAL;

CREATE TYPE salesperson_typ UNDER person_typ
(salesperson_id NUMBER, salary NUMBER, NoOfSale NUMBER);

CREATE TYPE customer_typ UNDER person_typ
(customer_id NUMBER, TotalPurchase NUMBER);

CREATE TABLE person_obj OF person_typ
NESTED TABLE phones STORE AS phones_tab;

My questions are:

1. I have created an object table person_obj of person_typ.

I have not created object tables of subtypes salesperson_typ and customer_typ and want to store data related to both in person_obj.

What is the difference between storing data in an object table of parent type and object table of subtypes?

In which case should I consider storing data of all subtypes in an object table of parent type instead of object tables of individual subtypes?

2. Second question is regarding validating the column values before the creation of object instance.

Suppose before creating an instance of salesperson_typ, I want to check if salary is NOT NULL and greater than 0.

I guess constructor is the only option to achieve this but how full-proof it is if constructors are used for this purpose?

Are there any alternate ways?

I didn't get answers to these questions anywhere hence thought of asking you.

Thanks in advance for your time.

Regards,
Ramesh