Check constraints and rules promote consistency. Because they are implemented once, in the table DDL, each constraint is always enforced. Constraints written in an application program, on the other hand, must be executed by each program that modifies the data to which the constraint applies. Usually the constraint must be coded into many programs. This can cause code duplication and inconsistent maintenance resulting in inaccurate business rule support.
Rules further promote consistency because one rule can be coded that is bound to multiple columns.
The overall impact of check constraints will be to increase application development productivity. Synopsis Check constraints and rules provide a very powerful vehicle for supporting business rules in SQL Server databases. They are non-bypassable and therefore provide better data integrity than corresponding logic programmed into application programs. Inc. All rights reserved.