DBMS Objective Questions and Answers - Set 2

This DBMS quiz contains carefully curated objective questions with correct answers and clear explanations. It is designed for computer science students, backend developers, and interview preparation, focusing on database design, SQL internals, transactions, indexing, and performance tuning. This is part 2 of the series.

Practice DBMS MCQs with Detailed Explanations

Answer at least 12 questions to submit and verify answers.

16 Which SQL command is DDL? Easy

INSERT

UPDATE

CREATE

SELECT

17 Which join returns unmatched rows from the left table? Medium

Inner join

Right join

Left outer join

Cross join

18 Which problem is addressed by multiversion concurrency control? High

Deadlock

Starvation

Read-write conflicts

Index fragmentation

19 What is the main disadvantage of bitmap indexes? Medium

High lookup time

Poor compression

Inefficient for high-cardinality columns

Cannot support range queries

20 Which SQL clause filters grouped data? Medium

WHERE

HAVING

GROUP BY

ORDER BY

21 Which failure requires redo during recovery? High

Transaction abort

System crash

Deadlock

Logical error

22 Which key uniquely identifies a tuple? Medium

Foreign key

Candidate key

Composite key

Super key

23 Which join produces maximum number of rows? Medium

Inner join

Left join

Right join

Cross join

24 Which schedule avoids cascading rollback? High

Recoverable

Cascadeless

Serializable

Strict

25 Which index is automatically created with primary key? Medium

Sparse index

Dense index

Clustered index

Secondary index

26 Which SQL function returns NULL if input is NULL? Medium

COUNT

SUM

AVG

MAX

27 Which normal form removes multivalued dependency? High

3NF

BCNF

4NF

5NF

28 Which problem occurs when two transactions update same data simultaneously? Medium

Dirty read

Lost update

Phantom read

Non-repeatable read

29 Which clause is mandatory with GROUP BY? Medium