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. How do you rename a column in the result set?

A) RENAME

B) USING

C) ALIAS

D) AS

2 / 30

2. What does the REVOKE command do?

A) Deletes user accounts

B) Creates a backup of permissions

C) Denies access to the database

D) Removes permissions from a user

3 / 30

3. Which SQL command is used to grant permissions to a user?

A) ASSIGN

B) PERMIT

C) ALLOW

D) GRANT

4 / 30

4. How can user activity be restricted during maintenance?

A) By switching to read-only mode

B) By locking the database

C) By revoking all permissions

D) By shutting down the database

5 / 30

5. What is the primary purpose of a database schema?

A) To store backup files

B) To define the structure of the database

C) To grant user permissions

D) To execute SQL queries

6 / 30

6. Which SQL keyword is used to combine results from multiple queries?

A) EXCEPT

B) UNION

C) JOIN

D) INTERSECT

7 / 30

7. Why are foreign keys important in database design?

A) They act as composite keys

B) They enforce referential integrity

C) They improve query performance

D) They reduce redundancy

8 / 30

8. What does the LIKE operator do?

A) Deletes records

B) Matches a pattern in a string

C) Sorts data

D) Joins tables

9 / 30

9. Which normal form eliminates transitive dependency?

A) 1NF

B) 2NF

C) 4NF

D) 3NF

10 / 30

10. What is the purpose of an index in SQL?

A) To store duplicate data

B) To ensure data integrity

C) To sort data

D) To speed up data retrieval

11 / 30

11. How do you add a new column to an existing table?

A) ADD COLUMN

B) UPDATE TABLE

C) ALTER TABLE

D) INSERT COLUMN

12 / 30

12. What is the role of a public key in asymmetric encryption?

A) To create indexes

B) To encrypt data

C) To store database logs

D) To decrypt data

13 / 30

13. What is the first step in database normalization?

A) Eliminating redundant data

B) Adding composite keys

C) Removing foreign keys

D) Ensuring all columns are atomic

14 / 30

14. How does database mirroring enhance security?

A) By replicating data to a standby server

B) By auditing user activities

C) By preventing SQL injection

D) By encrypting data

15 / 30

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

A) UNIQUE

B) DISTINCT

C) FILTER

D) GROUP BY

16 / 30

16. How is sensitive data protected in a database?

A) By auditing and monitoring activities

B) All of the above

C) By using encryption

D) By limiting user access

17 / 30

17. What type of dependency does 3NF eliminate?

A) Transitive dependency

B) Multivalued dependency

C) Circular dependency

D) Partial dependency

18 / 30

18. What is the result of a CROSS JOIN?

A) Union of two tables

B) Intersection of two tables

C) Cartesian product of two tables

D) Difference of two tables

19 / 30

19. What is SQL injection?

A) A way to encrypt database records

B) A database optimization technique

C) A method of creating backups

D) A security vulnerability allowing malicious SQL code execution

20 / 30

20. Which command is used to add new rows to a table?

A) ADD

B) INSERT

C) ALTER

D) UPDATE

21 / 30

21. What does 'principle of least privilege' mean in database security?

A) Allowing all users full database access

B) Removing unused tables and columns

C) Encrypting sensitive data

D) Assigning minimum access necessary for users

22 / 30

22. Which SQL function is used to count the number of rows in a table?

A) SUM()

B) ROWCOUNT()

C) TOTAL()

D) COUNT()

23 / 30

23. What is a security patch in database systems?

A) A tool to optimize queries

B) A fix for identified vulnerabilities

C) A backup of the database

D) A new feature added to the database

24 / 30

24. In a database table, what does 'redundancy' mean?

A) Efficient indexing

B) Optimal storage utilization

C) Duplicate or repetitive data

D) Data integrity

25 / 30

25. What is a window function in SQL?

A) A function that partitions data for analysis

B) A function that operates on a subset of rows

C) A function that performs calculations across a window of rows

D) All of the above

26 / 30

26. What does the HAVING clause do?

A) Deletes grouped data

B) Filters grouped data

C) Joins tables

D) None of the above

27 / 30

27. Which command is used to remove a user in SQL?

A) DROP USER

B) ALTER USER

C) REMOVE USER

D) DELETE USER

28 / 30

28. What does the NOT IN operator do?

A) Sorts rows

B) Filters rows

C) Excludes values from a list

D) Joins tables

29 / 30

29. What is a composite key?

A) A foreign key with a single column

B) A key used for indexing

C) A temporary key

D) A primary key consisting of multiple columns

30 / 30

30. Which normal form eliminates partial dependency?

A) BCNF

B) 3NF

C) 1NF

D) 2NF

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