This constraint will ensure that no employee can earn more commission than salary. The primary benefit is the ability to enforce business rules directly in each database without requiring additional application logic. Once defined, the business rule is physically implemented and can not be bypassed. This effectively minimizes the amount of code that must be written by the programming staff. With the significant application backlog within most organizations, this can be the most crucial reason to utilize check constraints.
Check constraints provide better data integrity.
When business rules are enforced using application programming logic instead, the rules can not be checked during ad hoc processes. Check constraints promote consistency. Because they are implemented once, in the table DDL, each constraint is always enforced. Constraints written in application logic, on the other hand, must be executed by each program that modifies the data to which the constraint applies. This can cause code duplication and inconsistent maintenance resulting in inaccurate business rule support.