Explanation: Check and foreign constraints are used to constraint the table data. 5. Problems occurs if we don’t implement proper locking strategy
A. Dirty reads
B. Phantom reads
C. Lost updates
D. Unrepeatable reads
Answer:A
Explanation: Check and foreign constraints are used to constraint the table data. 5. Problems occurs if we don’t implement proper locking strategy
A. Dirty reads B. Phantom reads C. Lost updates D. Unrepeatable reads
Explanation: In a concurrent execution of these transactions, it is intuitively clear that they conflict, but this is a conflict not captured by our simple model. This situation is referred to as the phantom phenomenon, because a conflict may exist on “phantom” data. 6. Which of the following fixed database roles can add or remove user IDs?