SQL Quiz Test Online (30 random Questions) 2026

This quick 30-minute challenge consists of 30 random multiple-choice questions designed to test your knowledge across various SQL topics, including the introduction to databases, data manipulation and querying, database design and normalization, advanced SQL concepts, and database administration and security. Whether you’re a beginner or looking to expand your SQL expertise, this quiz will enhance your understanding of database management and querying skills.

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30 Minutes SQL Quiz Test Online

Welcome to the SQL Quiz! This quick 30-minute challenge consists of 30 random multiple-choice questions designed to test your knowledge across various SQL topics, including the introduction to databases, data manipulation and querying, database design and normalization, advanced SQL concepts, and database administration and security. Whether you're a beginner or looking to expand your SQL expertise, this quiz will enhance your understanding of database management and querying skills.

1 / 30

1. What is the default sorting order in SQL?

A) Ascending

B) Random

C) None

D) Descending

2 / 30

2. What does the NOT IN operator do?

A) Joins tables

B) Sorts rows

C) Excludes values from a list

D) Filters rows

3 / 30

3. What is a foreign key?

A) None of the above

B) A unique identifier for a table

C) A backup key

D) A key linking two tables

4 / 30

4. What is denormalization?

A) Normalizing a database to BCNF

B) Breaking tables into smaller parts

C) Combining tables to improve performance

D) Eliminating all keys from a table

5 / 30

5. What is the primary role of a database administrator (DBA)?

A) Developing mobile applications

B) Managing and securing the database system

C) Designing user interfaces

D) Writing application code

6 / 30

6. How do you sort query results?

A) FILTER

B) GROUP BY

C) SORT BY

D) ORDER BY

7 / 30

7. What does BCNF stand for?

A) Boyce-Codd Normal Form

B) Basic Composite Normal Form

C) Binary Conjugate Normal Form

D) None of the above

8 / 30

8. How does the SQL MERGE statement work?

A) Performs insert, update, or delete operations based on a condition

B) Merges two tables into one new table

C) Combines columns from two queries into one result set

D) Optimizes indexes for faster retrieval

9 / 30

9. Which of the following is not a type of SQL join?

A) INNER JOIN

B) OUTER JOIN

C) CROSS JOIN

D) FULL JOIN

10 / 30

10. What is a disaster recovery plan in database management?

A) A guide to install database software

B) A plan to optimize database queries

C) A strategy to recover data in case of failure

D) A method to grant user permissions

11 / 30

11. What is the difference between DELETE and TRUNCATE?

A) DELETE removes all rows; TRUNCATE removes specific rows

B) DELETE resets indexes; TRUNCATE does not

C) DELETE removes specific rows; TRUNCATE removes all rows

D) DELETE is faster than TRUNCATE

12 / 30

12. What does the term 'role-based access control' (RBAC) mean?

A) Backing up the database

B) Encrypting sensitive data

C) Assigning permissions to individual users

D) Granting access based on predefined roles

13 / 30

13. Which method helps protect against SQL injection?

A) Parameterized queries

B) Input validation

C) Using stored procedures

D) All of the above

14 / 30

14. How can unauthorized database access be prevented?

A) All of the above

B) By enforcing strong authentication methods

C) By regularly updating security patches

D) By implementing firewalls

15 / 30

15. What is a scalar subquery?

A) A subquery that returns a single value

B) A subquery that returns multiple rows

C) A subquery that updates data

D) A subquery used in joins

16 / 30

16. What is the purpose of the UNION operator?

A) Combines results of two queries

B) Filters duplicate rows

C) Deletes records

D) Joins tables

17 / 30

17. What is the purpose of database encryption?

A) To improve performance

B) To secure data from unauthorized access

C) To compress data

D) To create database backups

18 / 30

18. What is the maximum number of primary keys a table can have?

A) None

B) 2

C) Unlimited

D) 1

19 / 30

19. What is an anomaly in the context of databases?

A) A query optimization technique

B) A redundancy issue causing inconsistencies

C) A high-performance operation

D) A security issue

20 / 30

20. What is a view in SQL?

A) A key linking tables

B) None of the above

C) A physical table

D) A virtual table based on a query

21 / 30

21. Which command is used to remove duplicate rows in a query result?

A) DISTINCT

B) FILTER

C) UNIQUE

D) GROUP BY

22 / 30

22. Which SQL keyword is used to sort the result set?

A) SORT

B) GROUP BY

C) ORDER BY

D) FILTER

23 / 30

23. Which normal form eliminates transitive dependency?

A) 2NF

B) 4NF

C) 3NF

D) 1NF

24 / 30

24. Which clause is used to combine rows with the same values?

A) UNION

B) ORDER BY

C) GROUP BY

D) DISTINCT

25 / 30

25. Which SQL function can identify the current user?

A) SESSION_USER()

B) All of the above

C) USER()

D) CURRENT_USER()

26 / 30

26. Which normal form is also known as 2NF with additional conditions?

A) 5NF

B) BCNF

C) 3NF

D) 4NF

27 / 30

27. How is sensitive data protected in a database?

A) By auditing and monitoring activities

B) All of the above

C) By limiting user access

D) By using encryption

28 / 30

28. How do you find the highest value in a column?

A) HIGHEST()

B) MIN()

C) MAX()

D) TOP()

29 / 30

29. What is a subquery?

A) A query within another query

B) A type of join

C) None of the above

D) A temporary table

30 / 30

30. Which SQL command is used to modify a user's password?

A) MODIFY PASSWORD

B) CHANGE PASSWORD

C) ALTER USER

D) UPDATE PASSWORD

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