Data validation rules

- [Instructor] Validation rules allow you to control…what data gets saved in the database.…If you try and enter a value that isn't allowed…by the validation rule, then Access will display a warning…and allow you to fix the problem.…Let's put some validation rules into effect…on our CreditCards table.…First, let's open up the CreditCards table…and take a look at what rules we want to enforce.…I want to make sure that the ExpirationDate,…which is this column right here,…let's actually just go ahead and make it a little bit wider…so we can see the full header name.…I want to make sure that the date that gets put in here…is in the future.…I don't want the ability to enter in a credit card…that's already expired.…

Next, let's suppose that the hotel is only able…to accept MasterCard and Visa credit cards.…We can create a validation rule on the CardType column…that enforces that rule.…We want to make sure that we don't enter in a card…from an unsupported merchant.…Let's make both of those changes,…and we'll do that in Design View.…