How can we calculate a field on the basis of membership point and purchase history-can we use a declare expression which in turn calls a decision table to calculate the field.(but here i am unable to find how decision table will help or should it be a general sum in declare expression?)
If the field is calculated using a mathematical formula (e.g., Membership Points + Purchase Amount × Multiplier), then a Declare Expression with the appropriate expression is the appropriate approach.
If the calculation depends on business conditions, decision table is appropriate choice
If you want to call a decision table in declare expression, you can first make the decision table in work class. (create → data model → decision table) , then go to casetype → datamodel. open that particular property , make it calculated read only and from the dropdown select existing decision table.