Add a Variable to an Existing Decision Table and Test the Rule

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Introduction

This process begins with an existing decision table with one in variable. The original decision table calculates a rate based only on the duration of the customer's account. This decision table calculates a rate based both on the duration of the account and the type of customer.

When you have completed the decision table, you should test it to ensure it behaves as you expect.

	QUICK STEPS
1	In the Parameters panel, click the + icon to add a parameter
2	Enter the parameter details
3	Right-click the expression column header and click Add Condition in Left
4	Enter the new column header description and expression
5	Create a new row condition
6	Define the description and expression for each row condition
7	Define the description and expression for the other conditions and results
8	Save the rule
9	Build the rule
10	Navigate to the scenario
11	Enter scenario values
12	Run the test
13	View the diagram
14	Create more test steps
15	Run all steps and check results
16	Save the scenario

Detailed Steps

Step 1. In the Parameters panel, click the + icon to add a parameter.

Open the decision table you want to update. You’re going to edit it so it uses multiple in variables. This means you have to add another variable (or parameter).

Step 2. Enter the parameter details.

This variable is going to be called “CustomerType”. The Direction is In and the Data Type is string.

Step 3. Right-click the expression column header and click Add Condition in Left.

Currently, this rule only uses the number of months to determine the interest rate. This example adds another factor to affect the rate: whether the account holder is regular or premium.

Step 4. Enter the new column header description and expression.

This column will use the CustomerType variable.

Step 5. Create a new row condition.

There will be two types. You need a row for each one.

Step 6. Define the description and expression for each row condition.

For this rule, Regular accounts will have the interest rates already defined.

Step 7. Define the description and expression for the other conditions and results.

For this rule, Premium accounts will have different rates.

This rule uses the same number of conditions for each customer type, but you can also have fewer conditions: you only have to cover all possible durations, not have the same number of possible rates.