Explore topic-wise MCQs in Database.

This section includes 3 Mcqs, each offering curated multiple-choice questions to sharpen your Database knowledge and support exam preparation. Choose a topic below to get started.

1.

Let transaction T1 has obtained a shared mode lock S on data item Q and transaction T2 has obtained an exclusive mode lock X on data item R Consider the following statement.I: T1 can read Q but cannot write Q.II. T2 can read R but cannot write R.Which of the above statements is / are valid?

A. Only I
B. Only II
C. Both I and II
D. Neither I nor II
Answer» B. Only II
Discussion
2.

In context of database, let T1 and T2 are two concurrent transactions. Consider the following sequence of operations on data X :T1 : READ(X) T2 : READ(X)T1 : WRITE(X) T2 : WRITE(X)This is a __________ problem.

A. Dirty Read
B. Lost Update
C. Incorrect Summary
D. Unrepeatable Read
Answer» B. Lost Update
Discussion
3.

Concurrency control in RDBMS is important for which of the following reasons ?

A. To ensure data integrity when updates occur to the database in a single -user environment.
B. To ensure data integrity when reads occur to the database in a single-user environment.
C. To ensure data integrity when updates occur to the database in a multi-user environment.
D. To ensure data integrity when reads occur to the database in a multi-user environment.
Answer» D. To ensure data integrity when reads occur to the database in a multi-user environment.
Discussion