Essential SQL Interview Questions for Freshers
Are you preparing for your first SQL interview? SQL (Structured Query Language) is a fundamental skill for database roles, and knowing the right questions can make a real difference. In this guide, you’ll explore 50+ SQL interview questions and answers for freshers, with examples, explanations, and tips to impress your interviewer.
What is SQL?
SQL (Structured Query Language) is used to communicate with relational databases. It is essential for database management, data retrieval, updates, and more. It’s a core skill for backend developers, data analysts, data engineers, and more.
Top SQL Interview Questions and Answers for Freshers
Let’s break down the most frequently asked SQL interview questions for freshers, grouped by category for easier understanding.
Basic SQL Interview Questions
Q1. What is SQL?
- SQL stands for Structured Query Language. It is used for storing, manipulating, and retrieving data in a relational database.
Q2. What are the different types of SQL statements?
DDL – Data Definition Language (
CREATE,DROP)DML – Data Manipulation Language (
INSERT,UPDATE,DELETE)DCL – Data Control Language (
GRANT,REVOKE)TCL – Transaction Control Language (
COMMIT,ROLLBACK)DQL – Data Query Language (
SELECT)
Q3. What is a primary key?
- A primary key is a unique identifier for a record in a table. It cannot have null or duplicate values.
Q4. What is a foreign key?
- A foreign key is a field that creates a relationship between two tables. It references the primary key in another table.
2. SQL Query Interview Questions
Q5. How do you select all data from a table?
SELECT * FROM table_name;
Q6. Write a query to get the top 5 salaries from a table.
SELECT DISTINCT salary
FROM employees
ORDER BY salary DESC
LIMIT 5;
Q7. What is the difference between WHERE and HAVING?
WHEREis used for filtering rows before grouping.HAVINGis used to filter data after grouping withGROUP BY.
Q8. How do you count the number of rows in a table?
SELECT COUNT(*) FROM table_name;
Q9. What is the use of GROUP BY?
GROUP BYis used to group rows with the same values in specified columns.
3. Advanced SQL Interview Questions
Q10. Explain JOIN and its types.
- A
JOINis used to combine rows from two or more tables.
Types of joins: INNER JOIN: Returns matching rows.
LEFT JOIN: Returns all rows from the left table and matched rows from the right.
RIGHT JOIN: Returns all rows from the right table and matched rows from the left.
FULL JOIN: Returns all rows when there is a match in one of the tables.
Q11. What is a subquery?
- A subquery is a query within another SQL query, often used in
WHEREorFROMclauses.
10 Practical SQL Query Examples
- Here are 10 SQL query interview examples commonly asked to freshers:
1. Select employees with salary > 50,000
SELECT * FROM employees WHERE salary > 50000;
2. Find total salary department-wise
SELECT department, SUM(salary) FROM employees GROUP BY department;
3. Retrieve all employees from ‘HR’ or ‘Sales’
SELECT * FROM employees WHERE department IN ('HR', 'Sales');
4. Count employees per department
SELECT department, COUNT(*) FROM employees GROUP BY department;
5. List employees joined after 2020
SELECT * FROM employees WHERE joining_date > '2020-01-01';
6. Get the highest salary
SELECT MAX(salary) AS highest_salary FROM employees;
7. Use INNER JOIN on employee and department tables
SELECT e.name, d.department_name
FROM employees e
INNER JOIN departments d ON e.department_id = d.id;
8. Get distinct job titles
SELECT DISTINCT job_title FROM employees;
9. Update salary of a specific employee
UPDATE employees SET salary = 70000 WHERE employee_id = 5;
10. Delete employees with no email address
DELETE FROM employees WHERE email IS NULL;
Best Practices for SQL Interviews
Understand query logic: Know why a query works, not just how.
Read the schema carefully: Always understand table relationships before writing a query.
Avoid SELECT *: Use specific columns to improve performance.
Be ready for real-world scenarios: Practice joining tables and using aggregate functions.
FAQs: SQL Interview Questions for Freshers
Q1. Is SQL easy to learn for freshers?
- Yes, SQL is beginner-friendly and widely used. Understanding basic commands like
SELECT,INSERT,UPDATE, andDELETEcan help freshers get started quickly.
Q2. What is the difference between DELETE, TRUNCATE, and DROP?
DELETE: Deletes specific rows; can be rolled back.TRUNCATE: Deletes all rows; cannot be rolled back.DROP: Removes the entire table.
Q3. How can I prepare for an SQL interview?
Practice SQL problems on platforms like LeetCode or HackerRank.
Understand schema diagrams.
Revise common SQL functions and commands.
Go through previous sql query interview questions.
Q4. Can I use SQL in data science or analytics roles?
- Absolutely! SQL is essential for data cleaning, analysis, and reporting in both fields.
Q5. What are common mistakes in SQL interviews?
Not handling NULL values properly
Using incorrect JOINs
Forgetting
GROUP BYwith aggregate functionsNot understanding performance implications
Conclusion
Mastering SQL interview questions for freshers is the key to landing your first role in tech, data analysis, or backend development. With the right preparation, even beginners can confidently answer both sql query interview questions and real-world problems.
Practice these questions, write your own queries, and review results carefully. And don’t forget — understanding why each query works will always give you the edge in interviews.
👉 Read more tech interview blogs on Freshy Blog for smart preparation tips!
