NOT INSTANTIABLE Object Types : Type Inheritance « Object Oriented « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. Object Oriented
3. Type Inheritance

You can mark an object type as NOT INSTANTIABLE, which prevents objects of that type from being created.

SQL> CREATE Or Replace TYPE ProductType AS OBJECT (
  2    id    NUMBER,
  3    make  VARCHAR2(15),
  4    model VARCHAR2(15)
  5  ) NOT FINAL NOT INSTANTIABLE;
  6  /

Type created.


SQL>
SQL> CREATE Or replace TYPE SubProduct1 UNDER ProductType (
  2    convertible CHAR(1)
  3  );
  4  /

Type created.

SQL> CREATE Or replace TYPE SubProduct2 UNDER ProductType (
  2    sidecar CHAR(1)
  3  );
  4  /

Type created.

SQL> CREATE TABLE product OF ProductType;

Table created.

SQL> CREATE TABLE cars OF SubProduct1;

Table created.

SQL> CREATE TABLE motorcycles OF SubProduct2;

Table created.

SQL>
SQL> INSERT INTO cars VALUES (
  2    SubProduct1(1, 'AA', 'MR2', 'Y')
  3  );

1 row created.

SQL>
SQL> INSERT INTO motorcycles VALUES (
  2    SubProduct2(1, 'BB', 'V-Rod', 'N')
  3  );

1 row created.

SQL> SELECT *
  2  FROM cars;

        ID MAKE            MODEL           C
---------- --------------- --------------- -
         1 AA              MR2             Y

SQL>
SQL> drop table product;

Table dropped.

SQL> drop table cars;

Table dropped.

SQL> drop table motorcycles;

Table dropped.

SQL>
SQL>
SQL>