Oracle Data Type constraints

How can I make a single element of a user type required?

The following is found in Oracle's Documentation to illustrate my question.

CREATE TYPE Person AS OBJECT (

   first_name VARCHAR2(15),
   last_name VARCHAR2(15),
   birthday DATE,
   home_address REF Address, -- shared with other Person objects

   phone_number VARCHAR2(15))
/

CREATE TABLE department (

   dept_name VARCHAR2(20),
   manager Person,
   location VARCHAR2(20))
/

What would I do if I wanted to manager.make first_name and manager.last_name required in the department table?

I found that I can add any constraint other than not null to a specific component.

CREATE TABLE department (

   dept_name VARCHAR2(20),
   manager Person,
   location VARCHAR2(20),
   Constraint ATest UNIQUE (manager.first_name, manager.last_name))
/

I realize that 'create table of' will allow 'not null' constraints to be implemented without hassle but then I would lose the benefit of inheritance if I had to create a new data type for
every table.

Thanks in advance for your expert help!

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Before you buy. Received on Thu Jun 29 2000 - 00:00:00 CDT