Preconditions

You can set preconditions and apply conditions throughout a decision table.

A decision table contains a preconditions section that lets you set:

• Variables that can be used in the decision table.
• Conditions that apply to an entire decision table.

If the precondition is not satisfied, none of the rules in the decision table can be evaluated.

For example, you could apply the following precondition to a decision table:

definitions
   set ‘wealthy customer’ to a customer
      where the average monthly balance of this customer 
                                      is more than $1 000 000
if
   the state of residence of ‘wealthy customer’ is NY

This precondition limits the scope of the rules in the decision table to only those customers with an average monthly balance of $1 000 000 and living in New York. It also allows you to create condition and action definitions using the variable wealthy customer.

Preconditions are tested before each rule in a table is executed.