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 a composite key?

A) None of the above

B) A combination of two or more columns as a key

C) A duplicate key

D) A single unique key

2 / 30

2. What is the result of a CROSS JOIN?

A) Cartesian product of two tables

B) Difference of two tables

C) Intersection of two tables

D) Union of two tables

3 / 30

3. What is the primary use of a FULL OUTER JOIN?

A) Combines rows with matching values only

B) Joins rows with null values only

C) Joins rows based on primary keys

D) Includes all rows from both tables, matching where possible

4 / 30

4. What is a subquery?

A) A query within another query

B) None of the above

C) A type of join

D) A temporary table

5 / 30

5. What is normalization in databases?

A) Increasing database size

B) Simplifying queries

C) Adding redundancy

D) Removing redundant data

6 / 30

6. What does the NOT IN operator do?

A) Sorts rows

B) Excludes values from a list

C) Filters rows

D) Joins tables

7 / 30

7. What does the LIKE operator do?

A) Deletes records

B) Sorts data

C) Matches a pattern in a string

D) Joins tables

8 / 30

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

A) A security issue

B) A query optimization technique

C) A redundancy issue causing inconsistencies

D) A high-performance operation

9 / 30

9. What is the default sorting order in SQL?

A) None

B) Descending

C) Ascending

D) Random

10 / 30

10. Which function returns the current date in SQL?

A) CURDATE()

B) GETDATE()

C) NOW()

D) All of the above

11 / 30

11. How do you combine data from multiple tables?

A) UNION

B) GROUP BY

C) JOIN

D) CONNECT

12 / 30

12. What is a security patch in database systems?

A) A fix for identified vulnerabilities

B) A backup of the database

C) A tool to optimize queries

D) A new feature added to the database

13 / 30

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

A) DISTINCT

B) ORDER BY

C) GROUP BY

D) UNION

14 / 30

14. What is the purpose of indexing in SQL?

A) To normalize tables

B) To increase redundancy

C) To speed up queries

D) To reduce redundancy

15 / 30

15. What is a view in SQL?

A) A key linking tables

B) None of the above

C) A virtual table based on a query

D) A physical table

16 / 30

16. What is a foreign key?

A) A key linking two tables

B) A backup key

C) A unique identifier for a table

D) None of the above

17 / 30

17. What is the purpose of a database firewall?

A) To monitor server performance

B) To manage user permissions

C) To block unauthorized access

D) To optimize query execution

18 / 30

18. Which SQL command is used to retrieve data from a database?

A) SELECT

B) DELETE

C) INSERT

D) UPDATE

19 / 30

19. What is the purpose of the ROW_NUMBER() function?

A) Assigns unique numbers to rows within a partition

B) Assigns ranks with gaps for duplicates

C) Creates a unique index

D) Calculates the total number of rows in a table

20 / 30

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

A) Duplicate or repetitive data

B) Optimal storage utilization

C) Data integrity

D) Efficient indexing

21 / 30

21. Which aggregate function calculates the sum of a column?

A) COUNT()

B) MAX()

C) AVG()

D) SUM()

22 / 30

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

A) FULL JOIN

B) OUTER JOIN

C) CROSS JOIN

D) INNER JOIN

23 / 30

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

A) Removing unused tables and columns

B) Allowing all users full database access

C) Assigning minimum access necessary for users

D) Encrypting sensitive data

24 / 30

24. What is the main drawback of normalization?

A) Slower write operations due to more joins

B) Reduces data integrity

C) Increases redundancy

D) Reduces database size

25 / 30

25. What is the purpose of the EXISTS clause in SQL?

A) To optimize queries

B) To create a temporary table

C) To verify the presence of rows in a subquery

D) To check if a table exists

26 / 30

26. Which normal form is achieved when every determinant is a candidate key?

A) 4NF

B) 3NF

C) BCNF

D) 5NF

27 / 30

27. Which SQL command is used to create a user?

A) ADD USER

B) CREATE USER

C) INSERT USER

D) NEW USER

28 / 30

28. Which of the following is a type of SQL statement?

A) Data Manipulation Language (DML)

B) All of the above

C) Data Definition Language (DDL)

D) Data Control Language (DCL)

29 / 30

29. Which normal form eliminates transitive dependency?

A) 3NF

B) 2NF

C) 4NF

D) 1NF

30 / 30

30. Which SQL clause is used to filter grouped data?

A) HAVING

B) GROUP BY

C) ORDER BY

D) WHERE

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