SQL is one of the most essential skills for every computer science student. Whether you are preparing for placements, working on projects, or becoming a backend/full-stack developer, mastering SQL helps you think logically and handle real-world data confidently. Here are the top 20 SQL queries every student must practice to build a strong foundation:
1. Create a Table
CREATE TABLE Students (id INT, name VARCHAR(50), age INT);
2. Insert Data
INSERT INTO Students VALUES (1, 'Arun', 20);
3. Select All Records
SELECT * FROM Students;
4. Select Specific Columns
SELECT name, age FROM Students;
5. WHERE Condition
SELECT * FROM Students WHERE age > 18;
6. UPDATE Query
UPDATE Students SET age = 21 WHERE id = 1;
7. DELETE Query
DELETE FROM Students WHERE id = 1;
8. ORDER BY
SELECT * FROM Students ORDER BY age DESC;
9. DISTINCT Values
SELECT DISTINCT age FROM Students;
10. COUNT(), MAX(), MIN(), AVG(), SUM()
SELECT COUNT(*), AVG(age) FROM Students;
11. GROUP BY
SELECT age, COUNT(*) FROM Students GROUP BY age;
12. HAVING Clause
SELECT age, COUNT(*)
FROM Students
GROUP BY age
HAVING COUNT(*) > 1;
13. LIKE Operator
SELECT * FROM Students WHERE name LIKE 'A%';
14. IN Operator
SELECT * FROM Students WHERE age IN (18, 19, 20);
15. BETWEEN
SELECT * FROM Students WHERE age BETWEEN 18 AND 22;
16. INNER JOIN
SELECT s.name, c.course
FROM Students s
JOIN Courses c ON s.id = c.student_id;
17. LEFT JOIN
SELECT s.name, c.course
FROM Students s
LEFT JOIN Courses c ON s.id = c.student_id;
18. SUBQUERY (Nested Query)
SELECT name FROM Students
WHERE age > (SELECT AVG(age) FROM Students);
19. CREATE VIEW
CREATE VIEW StudentView AS
SELECT name, age FROM Students;
20. ALTER TABLE
ALTER TABLE Students ADD email VARCHAR(50);
Comments
Post a Comment