SQL Quiz Test Online (30 random Questions) 2025

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. Which command is used to delete all rows from a table without removing the table?

A) REMOVE

B) TRUNCATE

C) DROP

D) DELETE

2 / 30

2. Which SQL function can identify the current user?

A) SESSION_USER()

B) CURRENT_USER()

C) USER()

D) All of the above

3 / 30

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

A) BCNF

B) 3NF

C) 5NF

D) 4NF

4 / 30

4. What happens if a table is not normalized?

A) Elimination of relationships

B) Improved performance

C) Increased redundancy and anomalies

D) Reduced storage usage

5 / 30

5. What does the GROUP BY clause do?

A) Filters rows

B) Sorts rows

C) Deletes duplicate rows

D) Groups rows with the same values

6 / 30

6. What does the HAVING clause do?

A) Joins tables

B) None of the above

C) Deletes grouped data

D) Filters grouped data

7 / 30

7. How do you combine data from multiple tables?

A) UNION

B) GROUP BY

C) JOIN

D) CONNECT

8 / 30

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

A) Assigning permissions to individual users

B) Backing up the database

C) Granting access based on predefined roles

D) Encrypting sensitive data

9 / 30

9. Which SQL clause is used to set a condition on aggregated data?

A) GROUP BY

B) HAVING

C) FILTER

D) WHERE

10 / 30

10. How do you check if a column contains NULL values?

A) HAS NULL

B) = NULL

C) IS NULL

D) CHECK NULL

11 / 30

11. Which type of dependency exists when a non-prime attribute depends on another non-prime attribute?

A) Partial dependency

B) Circular dependency

C) Multivalued dependency

D) Transitive dependency

12 / 30

12. Which normal form eliminates partial dependency?

A) BCNF

B) 1NF

C) 3NF

D) 2NF

13 / 30

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

A) SUM()

B) MAX()

C) COUNT()

D) AVG()

14 / 30

14. What is the primary advantage of a clustered index?

A) Faster insertions

B) Supports multiple indexes per table

C) Reduces storage requirements

D) Data is stored in order based on the index

15 / 30

15. What is a primary key?

A) A duplicate identifier for a table record

B) None of the above

C) A unique identifier for a table record

D) A command to fetch records

16 / 30

16. What is the purpose of database encryption?

A) To secure data from unauthorized access

B) To compress data

C) To improve performance

D) To create database backups

17 / 30

17. What does SQL stand for?

A) Structured Query Language

B) Standard Query Language

C) Simple Query Language

D) Sequential Query Language

18 / 30

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

A) Optimal storage utilization

B) Data integrity

C) Efficient indexing

D) Duplicate or repetitive data

19 / 30

19. Which command is used to create a new table in a database?

A) INSERT

B) CREATE TABLE

C) ADD TABLE

D) NEW TABLE

20 / 30

20. What is the result of normalization up to BCNF?

A) Completely eliminates redundancy

B) Ensures every determinant is a candidate key

C) Optimizes performance for all queries

D) Allows multivalued attributes

21 / 30

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

A) ROWCOUNT()

B) TOTAL()

C) COUNT()

D) SUM()

22 / 30

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

A) INSERT COLUMN

B) ADD COLUMN

C) ALTER TABLE

D) UPDATE TABLE

23 / 30

23. Which function returns the current date in SQL?

A) CURDATE()

B) GETDATE()

C) NOW()

D) All of the above

24 / 30

24. What is the purpose of the BETWEEN operator?

A) Matches a range of values

B) Filters NULL values

C) Sorts rows

D) Joins tables

25 / 30

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

A) To decrypt data

B) To store database logs

C) To encrypt data

D) To create indexes

26 / 30

26. What is the purpose of the UPDATE command?

A) Insert new records

B) Modify existing records

C) Create tables

D) Delete records

27 / 30

27. How does a CROSS JOIN behave?

A) Joins rows with matching primary keys

B) Joins rows with null values

C) Matches rows from two tables based on a condition

D) Produces a Cartesian product of two tables

28 / 30

28. How does database mirroring enhance security?

A) By auditing user activities

B) By preventing SQL injection

C) By replicating data to a standby server

D) By encrypting data

29 / 30

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

A) FULL JOIN

B) INNER JOIN

C) CROSS JOIN

D) OUTER JOIN

30 / 30

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

A) INSERT USER

B) NEW USER

C) ADD USER

D) CREATE USER

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