Constraining Dependent Values
Another common kind of validation involves comparing two attributes in the same row. The next example enforces a rule, which says that an employee’s commission must be less than 500. This rule will be applied only when both the commission and salary are non-null, and it will be reevaluated when either the commission or the salary value changes. The enhanced Compare validation rule in Oracle JDeveloper 11g makes this check easy to implement.