Creating a Subfunction v13

The FUNCTION clause specified in the declaration section defines and names a subfunction local to that block.

The term block refers to the SPL block structure consisting of an optional declaration section, a mandatory executable section, and an optional exception section. Blocks are the structures for standalone procedures and functions, anonymous blocks, subprograms, triggers, packages, and object type methods.

The phrase the identifier is local to the block means that the identifier (that is, a variable, cursor, type, or subprogram) is declared within the declaration section of that block and is therefore accessible by the SPL code within the executable section and optional exception section of that block.

FUNCTION <name> [ (<parameters>) ]
RETURN <data_type>
{ IS | AS }
    [ PRAGMA AUTONOMOUS_TRANSACTION; ]
    [ <declarations> ]
  BEGIN
    <statements>
  END [ <name> ];

Where:

name

name is the identifier of the subfunction.

parameters

parameters is a list of formal parameters.

data_type

data_type is the data type of the value returned by the function’s RETURN statement.

PRAGMA AUTONOMOUS_TRANSACTION

PRAGMA AUTONOMOUS_TRANSACTION is the directive that sets the subfunction as an autonomous transaction.

declarations

declarations are variable, cursor, type, or subprogram declarations. If subprogram declarations are included, they must be declared after all other variable, cursor, and type declarations.

statements

statements are SPL program statements (the BEGIN - END block may contain an EXCEPTION section).

Examples

The following example shows the use of a recursive subfunction:

DECLARE
    FUNCTION factorial (
        n           BINARY_INTEGER
    ) RETURN BINARY_INTEGER
    IS
    BEGIN
        IF n = 1 THEN
            RETURN n;
        ELSE
            RETURN n * factorial(n-1);
        END IF;
    END factorial;
BEGIN
    FOR i IN 1..5 LOOP
        DBMS_OUTPUT.PUT_LINE(i || '! = ' || factorial(i));
    END LOOP;
END;

The output from the example is the following:

1! = 1
2! = 2
3! = 6
4! = 24
5! = 120