Top SQL Interview Questions and Answers Every Fresher Should Know

Introduction: Why SQL Skills Matter in Data Analytics

SQL, or Structured Query Language, is the foundation of every data analytics career. It is the most widely used language for managing and analyzing relational databases. Whether you’re just starting or preparing for an interview, understanding SQL Interview Questions and Answers is critical to landing your first job in data analytics.

SQL helps analysts clean, prepare, and analyze data effectively. Every data analytics interview includes a section that tests your SQL knowledge because it shows your ability to work with data directly.

At H2K Infosys, our Data Analytics classes online teach you SQL through hands-on projects, preparing you to answer real-world interview questions with confidence.

1. SQL Interview Questions and Answers: What Is SQL and Why Is It Used?

Answer:
SQL (Structured Query Language) is used to store, retrieve, and manage data in relational databases. It allows analysts to extract insights from massive datasets with simple commands.

Example:

SELECT * FROM customers WHERE country = 'USA';

Why it matters:
Almost every business relies on SQL for reporting, data analysis, and decision-making. That’s why this question is among the most common SQL Interview Questions and Answers asked to freshers.

2. SQL Interview Questions and Answers: Explain the Types of SQL Commands

Top SQL Interview Questions and Answers Every Fresher Should Know

Answer:
SQL commands fall into five main categories:

Type	Description	Example
DDL (Data Definition Language)	Defines database structure	CREATE, ALTER, DROP
DML (Data Manipulation Language)	Manages data	INSERT, UPDATE, DELETE
DQL (Data Query Language)	Retrieves data	SELECT
DCL (Data Control Language)	Controls permissions	GRANT, REVOKE
TCL (Transaction Control Language)	Manages transactions	COMMIT, ROLLBACK

This question is another favorite in SQL Interview Questions and Answers because it checks your command over SQL fundamentals.

3. SQL Interview Questions and Answers: What Is the Difference Between SQL and MySQL?

Answer:

SQL is the standard programming language for databases.
MySQL is a software that uses SQL to manage databases.

This question appears often in SQL Interview Questions and Answers to test your understanding of SQL as a language versus a database management tool.

4. SQL Interview Questions and Answers: Explain Primary Key and Foreign Key

Answer:

Primary Key: Uniquely identifies each record in a table.
Foreign Key: Connects one table to another to establish a relationship.

Example:

CREATE TABLE department (

 dept_id INT PRIMARY KEY,

 dept_name VARCHAR(50)

);

CREATE TABLE employee (

 emp_id INT PRIMARY KEY,

 emp_name VARCHAR(50),

 dept_id INT,

 FOREIGN KEY (dept_id) REFERENCES department(dept_id)

);

This concept is frequently covered in SQL Interview Questions and Answers for freshers.

5. SQL Interview Questions and Answers: What Is Normalization?

Answer:
Normalization organizes data to reduce redundancy and improve integrity.

Types:

1NF – Remove repeating groups.
2NF – Ensure all attributes depend on the primary key.
3NF – Eliminate transitive dependency.

Interviewers love this question because normalization ensures efficient database design, making it one of the top SQL Interview Questions and Answers for beginners.

6. SQL Interview Questions and Answers: What Is the Difference Between WHERE and HAVING?

Answer:

WHERE: Filters rows before grouping.
HAVING: Filters after grouping.

Example:

SELECT department, COUNT(*) AS total_employees

FROM employees

GROUP BY department

HAVING COUNT(*) > 5;

7. SQL Interview Questions and Answers: What Are Joins in SQL?

Answer:
Joins combine rows from two or more tables based on related columns.

Type	Description
INNER JOIN	Returns matching rows from both tables
LEFT JOIN	Returns all rows from the left table
RIGHT JOIN	Returns all rows from the right table
FULL JOIN	Returns all rows when there is a match in either table

Example:

SELECT e.emp_name, d.dept_name

FROM employees e

INNER JOIN department d ON e.dept_id = d.dept_id;

8. SQL Interview Questions and Answers: What Are Aggregate Functions?

Answer:
Aggregate functions perform calculations on multiple rows and return a single result.

Common functions: COUNT(), SUM(), AVG(), MIN(), MAX()

Example:

SELECT department, AVG(salary) AS avg_salary

FROM employees

GROUP BY department;

9. SQL Interview Questions and Answers: What Is a Subquery?

Answer:
A subquery is a query inside another query.

Example:

SELECT name, salary

FROM employees

WHERE salary > (SELECT AVG(salary) FROM employees);

10. SQL Interview Questions and Answers: Difference Between DELETE, TRUNCATE, and DROP

Command	Action	Rollback?
DELETE	Removes selected rows	Yes
TRUNCATE	Removes all rows but keeps structure	No
DROP	Deletes table entirely	No

11. SQL Interview Questions and Answers: What Are Constraints?

Answer:
Constraints maintain data integrity within a database.

Types:

NOT NULL
UNIQUE
PRIMARY KEY
FOREIGN KEY
CHECK
DEFAULT

Example:

CREATE TABLE products (

 product_id INT PRIMARY KEY,

 price DECIMAL(10,2) CHECK (price > 0)

);

This question is almost always included in fresher-level SQL Interview Questions and Answers lists.

12. SQL Interview Questions and Answers: What Is an Index and Why Is It Used?

Answer:
An index speeds up data retrieval by allowing quick access to rows in a table.

Example:

CREATE INDEX idx_emp_name ON employees(emp_name);

Indexes improve query performance and are a vital part of advanced SQL Interview Questions and Answers.

13. SQL Interview Questions and Answers: What Are Views in SQL?

Answer:
A View is a virtual table that displays data from one or more tables.

Example:

CREATE VIEW high_salary_employees AS

SELECT emp_name, salary FROM employees WHERE salary > 90000;

Views simplify complex queries, making this one of the more conceptual SQL Interview Questions and Answers for analysts.

14. SQL Interview Questions and Answers: What Is the Difference Between UNION and UNION ALL?

Answer:

UNION combines results and removes duplicates.
UNION ALL includes duplicates.

Example:

SELECT city FROM customers

UNION

SELECT city FROM suppliers;

This is frequently featured among SQL Interview Questions and Answers that test data merging logic.

15. SQL Interview Questions and Answers: How to Find the Second-Highest Salary in a Table?

Answer:

SELECT MAX(salary) AS second_highest_salary

FROM employees

WHERE salary < (SELECT MAX(salary) FROM employees);

Real-World Relevance of SQL in Data Analytics

SQL isn’t just a programming skill it’s the language of data analytics. Professionals use it to clean, filter, and prepare data before visualization. Every tool from Excel to Tableau and Power BI integrates with SQL databases.

If you’re a beginner looking for data analytics classes online for beginners or a Google data analytics course, H2K Infosys offers interactive, project-based training that covers SQL, Excel, Python, and visualization tools.

Through data analytics training at H2K Infosys, you’ll:

Learn to write optimized SQL queries.
Practice with real datasets.
Solve real-world analytics case studies.
Get certified for job-ready skills.

Key Takeaways

SQL is essential for every data analytics professional.
Mastering these SQL Interview Questions and Answers builds both technical skill and confidence.
SQL knowledge helps you clean, analyze, and present data effectively.
Joining H2K Infosys’ Data Analytics classes online helps you gain hands-on experience through real industry projects.

Conclusion: Start Your SQL Journey with H2K Infosys

Learning SQL is your first step toward becoming a skilled data analyst. Understanding these SQL Interview Questions and Answers will give you a strong foundation for your interviews and your analytics career.

Enroll today in H2K Infosys’ online Data Analytics course and master SQL, Python, Excel, and visualization tools through practical, instructor-led sessions. Build confidence, gain expertise, and get job-ready in data analytics.