A function is a named program unit. It consists of three parts:

► Declaration Part - Defining the function name, calling parameters, return value type, local variables and local procedures. Declaration part is required.

► Execution Part - Defining execution logic with executable statements. Execution part is required.

► Exception Part - Defining error handling logic. Exception part is optional.

Here how a complete procedure should look like:

FUNCTION name (parameter_1, parameter_2) RETURN type AS

-- Declaration statements

BEGIN

-- Executable statements

RETURN value;

EXCEPTION

-- Error handling statements

END;