A bicycle rental shop, Velocipede Rides, is transitioning its booking records from a single flat-file spreadsheet to a relational database. The draft schema design is shown below:
| BicycleID | Model | HourlyRate |
|---|---|---|
| BIKE01 | Cruiser X | £5.00 |
| BIKE02 | TrailBlazer | £8.50 |
| CustomerID | Name | PhoneNumber |
|---|---|---|
| CUST801 | Alice Vance | 07700 900077 |
| CUST802 | Bob Miller | 07700 900088 |
| RentalID | CustomerID | BicycleID | RentalDate |
|---|---|---|---|
| RENT901 | CUST801 | BIKE01 | 12/05/2024 |
| RENT902 | CUST801 | BIKE02 | 14/05/2024 |
| RENT903 | CUST802 | BIKE01 | 15/05/2024 |
Which of the following statements correctly identifies a key advantage of this relational database structure over a single flat-file spreadsheet?
By designating PhoneNumberPhoneNumberPhoneNumber as a foreign key in the RentalRentalRental table, any updates to a customer's contact details are automatically propagated from the RentalRentalRental table back to the CustomerCustomerCustomer table.
It minimizes data redundancy by storing customer contact details once in the CustomerCustomerCustomer table, allowing multiple rental records to link to a single customer via the CustomerIDCustomerIDCustomerID foreign key.
It improves query performance by duplicating the ModelModelModel and HourlyRateHourlyRateHourlyRate fields from the BicycleBicycleBicycle table into the RentalRentalRental table, thereby eliminating the need for relational joins.
It guarantees entity integrity by allowing the primary key RentalIDRentalIDRentalID to contain null values during transactions where the customer has not yet chosen a bicycle.
38 exam-style questions on AQA GCSE Computer Science Relational databases. Each one has a worked solution and a mark scheme showing where the marks go.