CREATE TYPE BODY

CREATE TYPE BODY

Purpose

Use the CREATE TYPE BODY to define or implement the member methods defined in the object type specification. You create object types with the CREATE TYPE and the CREATE TYPE BODY statements. The CREATE TYPE statement specifies the name of the object type, its attributes, methods, and other properties. The CREATE TYPE BODY statement contains the code for the methods in the type.

For each method specified in an object type specification for which you did not specify the call_spec, you must specify a corresponding method body in the object type body.

Note: If you create a SQLJ object type, you cannot specify a type body. The implementation of the type is specified as a Java class.

See Also: CREATE TYPE on page 16-3 and ALTER TYPE on page 12-6 for information on creating and modifying a type specification

Prerequisites

Every member declaration in the CREATE TYPE specification for object types must have a corresponding construct in the CREATE TYPE or CREATE TYPE BODY statement.

To create or replace a type body in your own schema, you must have the CREATE TYPE or the CREATE ANY TYPE system privilege. To create an object type in another user’s schema, you must have the CREATE ANY TYPE system privileges. To replace an object type in another user’s schema, you must have the DROP ANY TYPE system privileges.

SQL Statements: CREATE TYPE to DROP ROLLBACK SEGMENT 16-25

CREATE TYPE BODY

Syntax

create_type_body::=

(procedure_declaration::= on page 16-26, function_declaration::= on page 16-26, constructor_declaration::= on page 16-27)

subprogram_declaration::=

procedure_declaration

MEMBER

function_declaration

STATIC

constructor_declaration

procedure_declaration::=

(call_spec::= on page 16-8) function_declaration::=

(call_spec::= on page 16-8)

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CREATE TYPE BODY

constructor_declaration::=

map_order_func_declaration::=

MAP

MEMBER function_declaration

ORDER

call_spec::=

Java_declaration

LANGUAGE

C_declaration

Java_declaration::=

JAVA NAME ’ string ’

C_declaration::=

SQL Statements: CREATE TYPE to DROP ROLLBACK SEGMENT 16-27

CREATE TYPE BODY

Semantics

OR REPLACE

Specify OR REPLACE to re-create the type body if it already exists. Use this clause to change the definition of an existing type body without first dropping it.

Users previously granted privileges on the re-created object type body can use and reference the object type body without being granted privileges again.

You can use this clause to add new member subprogram definitions to specifications added with the ALTER TYPE ... REPLACE statement.

schema

Specify the schema to contain the type body. If you omit schema, Oracle creates the type body in your current schema.

type_name

Specify the name of an object type.

IS | AS

MEMBER | STATIC

Specify the type of function or procedure subprogram associated with the object type specification.

You must define a corresponding method name, optional parameter list, and (for functions) a return type in the object type specification for each procedure or function declaration.

procedure_declaration, function_declaration, Declare a procedure or function subprogram.

constructor_declaration Declare a user-defined constructor subprogram. The RETURN clause of a constructor function must be RETURN SELF AS RESULT. This setting indicates that the most specific type of the value returned by the constructor function is the same as the most specific type of the SELF argument that was passed in to the constructor function.

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CREATE TYPE BODY

See Also:

■CREATE TYPE on page 16-3 for a list of restrictions on user-defined functions

■PL/SQL User’s Guide and Reference for information about overloading subprogram names within a package

■CREATE PROCEDURE on page 14-64, CREATE FUNCTION on page 13-52, and Oracle9i Application Developer’s Guide - Fundamentals for information on the components of type body

■Oracle9i Application Developer’s Guide - Object-Relational Features for information on and examples of user-defined constructors

pl/sql_block Declare the procedure or function.

See Also: PL/SQL User’s Guide and Reference

call_spec Specify the call specification ("call spec") that maps a Java or C method name, parameter types, and return type to their SQL counterparts.

The Java_declaration, ’string’ identifies the Java implementation of the method.

See Also:

map_order_func_declaration

You can declare either one MAP method or one ORDER method, regardless how many MEMBER or STATIC methods you declare. If you declare either a MAP or ORDER method, you can compare object instances in SQL.

If you do not declare either method, you can compare object instances only for equality or inequality. Instances of the same type definition are equal only if each pair of their corresponding attributes is equal.

SQL Statements: CREATE TYPE to DROP ROLLBACK SEGMENT 16-29

CREATE TYPE BODY

MAP MEMBER Clause

Specify MAP MEMBER to declare or implement a member function (MAP method) that returns the relative position of a given instance in the ordering of all instances of the object. A MAP method is called implicitly and specifies an ordering of object instances by mapping them to values of a predefined scalar type. PL/SQL uses the ordering to evaluate Boolean expressions and to perform comparisons.

If the argument to the MAP method is null, the MAP method returns null and the method is not invoked.

An object type body can contain only one MAP method, which must be a function. The MAP function can have no arguments other than the implicit SELF argument.

ORDER MEMBER Clause

Specify ORDER MEMBER to specify a member function (ORDER method) that takes an instance of an object as an explicit argument and the implicit SELF argument and returns either a negative, zero, or positive integer. The negative, positive, or zero indicates that the implicit SELF argument is less than, equal to, or greater than the explicit argument.

If either argument to the ORDER method is null, the ORDER method returns null and the method is not invoked.

When instances of the same object type definition are compared in an ORDER BY clause, Oracle invokes the ORDER MEMBER function_declaration.

An object specification can contain only one ORDER method, which must be a function having the return type NUMBER.

function_declaration Declare a function subprogram.

See Also: CREATE PROCEDURE on page 14-64 and CREATE FUNCTION on page 13-52 for the full syntax with all possible clauses

AS EXTERNAL AS EXTERNAL is an alternative way of declaring a C method. This clause has been deprecated and is supported for backward compatibility only. Oracle Corporation recommends that you use the call_spec syntax with the C_ declaration.

Examples

Several examples of creating type bodies appear in the "Examples" section of CREATE TYPE on page 16-19.

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CREATE TYPE BODY

Updating a Type Body: Example The following example shows how the type body of the data_typ object type (see "Object Type Examples" on page 16-19) must be modified when an attribute is added to the type (the PL/SQL is shown in italics):

ALTER TYPE data_typ

ADD MEMBER FUNCTION qtr(der_qtr DATE)

RETURN CHAR CASCADE;

CREATE OR REPLACE TYPE BODY data_typ IS

MEMBER FUNCTION prod (invent NUMBER) RETURN NUMBER IS BEGIN

RETURN (year + invent); END;

MEMBER FUNCTION qtr(der_qtr DATE) RETURN CHAR IS BEGIN

IF (der_qtr < TO_DATE(’01-APR’, ’DD-MON’)) THEN RETURN ’FIRST’;

ELSIF (der_qtr < TO_DATE(’01-JUL’, ’DD-MON’)) THEN RETURN ’SECOND’;

ELSIF (der_qtr < TO_DATE(’01-OCT’, ’DD-MON’)) THEN RETURN ’THIRD’;

ELSE

RETURN ’FOURTH’; END IF;

END; END;

/

END;

SQL Statements: CREATE TYPE to DROP ROLLBACK SEGMENT 16-31