SQL Question & Answer Practice

SQL Practice – Questions & Answers

Beginner Level

Q16. COUNT function.

SELECT COUNT(*) FROM students;

Q17. MAX value.

SELECT MAX(marks) FROM students;

Q18. MIN value.

SELECT MIN(marks) FROM students;

Q19. AVG value.

SELECT AVG(marks) FROM students;

Q20. LIKE operator.

SELECT * FROM students WHERE name LIKE 'A%';

Q21. BETWEEN.

SELECT * FROM students WHERE age BETWEEN 18 AND 25;

Q22. IN operator.

SELECT * FROM students WHERE city IN('Delhi','Mumbai');

Q23. LIMIT.

SELECT * FROM students LIMIT 5;

Q24. Alias.

SELECT name AS student_name FROM students;

Q25. ALTER add column.

ALTER TABLE students ADD city VARCHAR(20);

Q26. PRIMARY KEY.

id INT PRIMARY KEY

Q27. FOREIGN KEY.

FOREIGN KEY(sid) REFERENCES students(id);

Q28. UNIQUE constraint.

email VARCHAR(50) UNIQUE

Q29. INDEX.

CREATE INDEX idx_name ON students(name);

Q30. CASE statement.

CASE WHEN age>18 THEN 'Adult' ELSE 'Minor' END