Example 1: Invoking a randomizer

This example shows how an external component returns a random number for a lottery. Each customer booking a reservation automatically gets a free lottery number.

The component uses an input parameter to determine between which number and zero a random number must be found. In this example, lottery numbers between 0 and 10000 are returned.

The example uses the Travel Agency case .

Component Name	USMATH
Component Prog ID	USMathProject.USMath
Method Name	RANDOM
Physical Method Name	Random
Parameters of RANDOM	In - Long Integer Return - Long Integer

In the data model, to the RESERVATION table, add a LOTTERY_NO column based on a regular NUMBER(8) domain.

Add a constraint:

Constraint Name	ASSIGN_LOTTERY_NO
Message	Lottery no. assigned.
Transition Table	RESERVATION
Fire on Insert	Always
Fire on Delete	Never
Fire on Update	Never

Set the SQL statement to:

UPDATE    reservation
SET       lottery_no =
(
    INVOKE   usmath.random WITH
    SELECT   10000
)

Description of functionality

The randomizer component returns a random integer between 0 and the input parameter.

Code of invoked subprogram

Public Function Random(maxi As Integer) As Integer
Randomize
Random = Int(maxi * Rnd)
End Function