SQL is one of the most important skills for anyone who wants to work with data, software, or databases. Whether you want to become an SQL developer, data analyst, backend developer, or get any role that deals with databases, understanding SQL is a must. Many companies use SQL every day, and that is why SQL interview questions are very common in job interviews for both freshers and experienced professionals.
In 2026, the demand for SQL is still growing. Companies want people who can read data, manage data, and write clean SQL queries. If you are preparing for your next interview, this guide will help you. Here, you will find 50+ SQL interview questions and answers, including basic SQL interview questions, SQL query interview questions, and SQL interview questions for experienced candidates. The language is kept simple so that even freshers can understand easily.
Why SQL Matters in 2026
SQL remains the backbone of almost every database system. From small companies to big tech firms, everyone uses SQL to store data, update data, and retrieve data. SQL is used in:
- Banking
- E-commerce
- Apps and websites
- Data analytics
- Software development
- Cloud platforms
Because of this, sql jobs for freshers and professionals continue to grow every year.
Now let’s look at the top SQL questions asked in interviews
Top SQL Interview Questions and Answers
Below are 50+ easy-to-understand SQL interview questions and answers to help you prepare.
Basic SQL Interview Questions for Freshers
1. What is SQL?
SQL stands for Structured Query Language. It is used to store, manage, and retrieve data from a database.
2. What is a database?
A database is a place where data is stored in an organized manner.
3. What is a table in SQL?
A table stores data in rows and columns.
4. What is a primary key?
A primary key is a unique value that identifies each row in a table.
5. What is a foreign key?
A foreign key connects two tables and creates a relationship between them.
6. What is a unique key?
A unique key ensures that no two rows have the same value in that column.
7. What is a NULL value?
NULL means no value has been entered.
8. What is a constraint?
Constraints control what type of data can go into a table.
9. What is SQL syntax?
SQL syntax includes keywords like SELECT, INSERT, UPDATE, DELETE.
10. What are the types of SQL commands?
- DDL – Data Definition Language
- DML – Data Manipulation Language
- DCL – Data Control Language
- TCL – Transaction Control Language
SQL Query Interview Questions
11. What is the SELECT statement?
It retrieves data from a table.
Example:
SELECT * FROM employees;
12. How do you filter data in SQL?
Using the WHERE clause.
SELECT * FROM employees WHERE salary > 30000;
13. How to sort data?
Using ORDER BY.
SELECT * FROM employees ORDER BY name ASC;
14. How to insert data?
INSERT INTO employees (name, salary) VALUES ('Rahul', 45000);
15. How to update data?
UPDATE employees SET salary = 50000 WHERE id = 1;
16. How to delete data?
DELETE FROM employees WHERE id = 1;
17. What is LIKE used for?
It helps in pattern matching.
SELECT * FROM students WHERE name LIKE 'A%';
18. What is IN used for?
To match multiple values.
SELECT * FROM employees WHERE department IN ('IT', 'HR');
19. What is BETWEEN used for?
To select results within a range.
SELECT * FROM products WHERE price BETWEEN 100 AND 500;
20. What is COUNT()?
It returns the number of rows.
SELECT COUNT(*) FROM orders;
SQL Interview Questions for Experienced Professionals
21. What is a join?
Joins combine data from two or more tables.
22. What are the types of joins?
- INNER JOIN
- LEFT JOIN
- RIGHT JOIN
- FULL JOIN
23. What is INNER JOIN?
It returns matching data from both tables.
24. What is LEFT JOIN?
It returns all data from the left table and matching data from the right table.
25. What is GROUP BY?
It groups rows that have the same value.
SELECT department, COUNT(*) FROM employees GROUP BY department;
26. What is HAVING?
Used to filter grouped data.
SELECT department, COUNT(*)
FROM employees
GROUP BY department
HAVING COUNT(*) > 5;
27. What is an index?
An index improves the speed of data searching.
28. What is a view?
A view is a virtual table created using a query.
29. What is a stored procedure?
A stored procedure is a reusable block of SQL code.
30. What is a trigger?
A trigger runs automatically when an event happens (insert, update, delete).
Advanced SQL Questions
31. What is normalization?
It organizes data to reduce duplication.
32. What are normal forms?
1NF, 2NF, 3NF, BCNF.
33. What is denormalization?
Adding duplicate data to improve read speed.
34. What is ACID in SQL?
Atomicity, Consistency, Isolation, Durability.
35. What is a transaction?
A transaction is a group of SQL operations that run together.
36. What is UNION?
Combines results from two queries.
37. What is UNION ALL?
Same as UNION but keeps duplicates.
38. What is a subquery?
A query inside another query.
39. What is COALESCE?
Returns the first non-null value.
40. What is CASE in SQL?
A conditional statement similar to IF-ELSE.
More SQL Questions (Useful for Interviews)
41. What is the difference between DELETE and TRUNCATE?
DELETE removes rows one by one,
TRUNCATE removes all rows at once.
42. What is the difference between DROP and TRUNCATE?
DROP deletes the whole table,
TRUNCATE deletes only the data.
43. What is a composite key?
A key made from two or more columns.
44. What is an alias?
A temporary name given to a table or column.
45. What is a cursor?
A pointer that moves through query results one row at a time.
46. What is a temporary table?
A short-term table that exists only for a session.
47. What is a schema?
A collection of database objects.
48. How do you find duplicate records?
Using GROUP BY and HAVING.
SELECT name, COUNT(*)
FROM students
GROUP BY name
HAVING COUNT(*) > 1;
49. How do you find the highest salary?
SELECT MAX(salary) FROM employees;
50. How to find the second-highest salary?
SELECT MAX(salary)
FROM employees
WHERE salary < (SELECT MAX(salary) FROM employees);
51. What is the LIMIT clause?
It is used to restrict results.
52. What is DISTINCT?
It removes duplicate values.
FAQs About SQL
1. What is SQL and why is it used?
SQL is used to store, manage, and retrieve data in databases. Almost every company uses SQL to handle large amounts of information.
2. Is Excel a SQL database?
No. Excel is a spreadsheet tool. SQL databases are more powerful and used for storing large data.
3. Which is easy, SQL or Excel?
For beginners, Excel feels easier. But SQL becomes easy with practice and is more powerful for data jobs.
4. What are SQL skills?
SQL skills include writing queries, joins, filtering data, sorting data, creating tables, and working with databases.
5. Can I learn SQL in 3 months?
Yes. With daily practice, you can learn SQL basics and even advanced queries within 3 months.
6. Is SQL still in demand in 2026?
Yes. SQL will remain in high demand because companies will always need clean and reliable data, and SQL is the best tool for it.
Final Words
SQL is one of the strongest and most stable career skills for 2026 and beyond. If you prepare these top SQL interview questions, you will feel confident in your next interview. Whether you are a fresher or an experienced candidate, knowing SQL well can help you move ahead in your career.
