The correct answer is: B. means change all the related records in child tables if the record in parent table is changed.
A cascade update is a database operation that automatically updates related records in other tables when a record in the parent table is updated. For example, if you have a table of customers and a table of orders, and you update a customer’s name, the cascade update option would automatically update the customer’s name in all of the orders that the customer has placed.
The cascade update option is useful when you want to ensure that all of the related records are kept up-to-date. However, it is important to use it with caution, as it can cause unexpected results if the related records are not properly defined.
Option A is incorrect because it does not describe the cascade update option. The cascade update option does not mean “do not change the value in the primary key field if that record has related records in another table.” Instead, it means “change all the related records in child tables if the record in parent table is changed.”
Option C is incorrect because it is a combination of Option A and Option B. The cascade update option is not both “do not change the value in the primary key field if that record has related records in another table” and “change all the related records in child tables if the record in parent table is changed.” Instead, it is only “change all the related records in child tables if the record in parent table is changed.”
Option D is incorrect because it is the only option that is not a correct description of the cascade update option. The cascade update option is not “None of above.” Instead, it is “change all the related records in child tables if the record in parent table is changed.”