Supertype and Subtypes

Question

Hello,
I created an employees table with 3 types, although when I insert the values, it works but doesn't display the last value which is from a different type. Any idea how to fix this?
DROP TYPE employees_type FORCE;
DROP TYPE hourly_employees FORCE;
DROP TYPE salaried_employee FORCE;
DROP TYPE consultant_employee FORCE;
DROP TABLE employees;
CREATE OR REPLACE TYPE employees_type AS OBJECT
emp_id CHAR(4) ,
fname VARCHAR2(20),
lname VARCHAR2(20),
date_hired DATE ,
emp_type CHAR(1)
)NOT FINAL;
CREATE OR REPLACE TYPE hourly_employees UNDER employees_type
hourly_rate NUMBER(6,2)
)NOT FINAL;
CREATE OR REPLACE TYPE salaried_employee UNDER employees_type
annual_salary NUMBER(9,2),
stock_option     CHAR(1)
)NOT FINAL;
CREATE OR REPLACE TYPE consultant_employee UNDER employees_type
contract_number NUMBER,
billing_rate     NUMBER(8,2)
CREATE TABLE employees OF employees_type;
INSERT INTO employees
VALUES (hourly_employees(1234,null,null,null,null,0));

Answer 1

SQL> SELECT TREAT(VALUE(e) AS hourly_employees)
  2    FROM employees e
  3   WHERE VALUE(e) IS OF(hourly_employees);
TREAT(VALUE(E)ASHOURLY_EMPLOYEES)(EMP_ID, FNAME, LNAME, DATE_HIRED, EMP_TYPE, HOURLY_RATE)
HOURLY_EMPLOYEES('1234', NULL, NULL, NULL, NULL, 0)or
SQL> SELECT e.*,
  2         TREAT(VALUE(e) AS hourly_employees).hourly_rate AS hourly_rate
  3    FROM employees e
  4   WHERE VALUE(e) IS OF(hourly_employees);
EMP_ FNAME                LNAME                DATE_HIR E HOURLY_RATE
1234                                                                0Regards