Which of the following database terms is described in the statement below? “It prevents the current database
operation from reading or writing a data item whilethe data item is being accessed by another operation.”

A.
Lock

B.
Encryption

C.
Constraint

D.
Deadlock

Explanation:
Lock is the process to prevent the current databaseoperations from reading and writing a data while that data
item is being accessed by another operation. A lockis used when multiple users need to access a database
concurrently. It prevents data from getting corruptor invalidated, when multiple users try to write to the
database. When a lock is applied, a single user canonly modify that record to which the lock is applied. It gives
the user exclusive access to the record until the lock is released. Locking also prevents reading of unfinished
(uncommitted) data.
Answer B is incorrect. Encryption provides an additional security layer, protecting the data from unauthorized
viewing with the help of an algorithm called cipher. Even if access to the database is obtained, it will not be
easy to decipher encrypted data into a readable form. Answer D is incorrect. A deadlock is a situationwherein
two or more competing actions wait for the other tofinish, and neither ever does.
Answer C is incorrect. A constraint enforces the integrity of a database. It defines the rules regarding the
values allowed in the columns of a table. A constraint is the standard mechanism for enforcing integrity.