Chapter 9. Object Technology

Oracle8 ushered us into the brave new world of object-oriented programming. . .almost. Since Oracle is, after all, a relational database, much of the object technology introduced in the Oracle8 (as well as the Oracle8i) release is a hybrid between true object data and relational data. The CREATE TYPE command, for example, looks suspiciously like a familiar record or table, with the exception that you can now include methods (procedures and functions) that act on the object’s attributes (columns and fields). This chapter tests your understanding of object types and your ability to apply object-oriented principles when designing a data structure.

Beginner

9-1.

True or false? An object type:

  1. Is a database construct created via the CREATE TYPE statement.

  2. Defines a data structure with attributes, each having a single datatype.

  3. Defines legal methods or operations on the object’s attributes.

  4. Is a template only and holds no actual data.

9-2.

True or false? An object type can serve as the datatype of:

  1. Each of the rows in a table.

  2. A column in a table.

  3. A PL/SQL variable.

  4. A PL/SQL module’s IN, OUT, or RETURN parameter.

  5. A index-by table, nested table, or VARRAY.

  6. A “field” in a PL/SQL record variable.

9-3.

A constructor is a special method that creates an instance of an object from an object type. True or false? A constructor:

  1. Has the same name as its object type.

  2. Is a function rather than a procedure.

  3. Returns an instance of its object type.

  4. Has one parameter per attribute of the object ...

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