SQL or Structured Query Language has been considered one of the important technical competencies required from data analysts, software engineers, business intelligence experts, or database administrators. With all the technological developments that have taken place, one of the most important skill sets needed for job roles like Data Analyst, SQL Developer, Backend Developer, or Data Engineer is SQL.

Are you prepared for your coming interviews? Find this list of SQL Interview Questions, which will surely help you land interviews with your database management skills.

Where is the difference between WHERE and HAVING?

The Where Clause appears before the Aggregate Function, while the Having Clause appears after the Aggregate Function.

Example:

SELECT Department, COUNT(*)

FROM Employees

GROUP BY Department

HAVING COUNT(*) > 5

2. What is a SQL JOIN?

SQL Joins are used to join data from various tables.

Common types include:

• INNER JOIN
• LEFT JOIN
• RIGHT JOIN
• FULL OUTER JOIN

During interviews, interviewees are asked about the practical use of joins within a real business case.

3. Difference between RANK() and DENSE_RANK()

Both functions rank the records.

However, in the event of a tie, the RANK() command does not give numbers, but rankings.

The DENSE_RANK() command gives ranking based on values in ascending order, without skipping any value.

This is a common SQL interview question to test the candidate’s knowledge.

4. What is a Common Table Expression?

CTEs increase the ease of writing complex queries.

Example:

WITH HighSalary AS (

SELECT * FROM Employees

WHERE Salary > 50000

)

SELECT * FROM HighSalary;

5. What is a Window Function?

Window functions calculate over a window of rows, without grouping them.

Examples include:

ROW_NUMBER()

RANK()

DENSE_RANK()

LEAD()

LAG()

These are important functions for contemporary Data Analytics jobs.

6. How do you get rid of duplicate data in a database table?

ROW_NUMBER() is a popular method.

WITH DuplicateRows AS (

SELECT *,

ROW_NUMBER() OVER (PARTITION BY Email ORDER BY ID) AS RowNum

FROM Customers

)

DELETE FROM DuplicateRows

WHERE RowNum > 1;

7. ACID Properties are what

ACID provides a reliable transaction to a database.

Atomicity – Either all operations are completed, or none.

Consistency – Data is valid.

Transactions are isolated – no interference with each other.

Durability – Data that is committed is permanently kept.

8. What is Indexing in SQL

An index may improve query performance by reducing the number of records returned.

Benefits:

• Faster searches
• Improved query execution
• Better database performance

But excessive indexing can adversely affect insertions and modifications.

9. How do you write a query to get the second-highest salary?

SELECT MAX(Salary)

FROM Employees

WHERE Salary <

(SELECT MAX(Salary)

FROM Employees);

This is one of the most frequently asked SQL interview questions.

10. What is the Difference Between Delete, Truncate, and Drop?

Knowing these differences is key to database-related jobs.

Hands-on SQL Interview Tips for 2025

The best trainers suggest concentrating on the skills instead of on the responses.

Before Your Interview:

• Do everyday SQL queries to practice.
• SQL Questions on LeetCode, HackerRank, etc.
• Joins, CTEs, Window Function, and Indexing should be known.
• Know how to explain query optimisation techniques.
• Write queries without assistance from query autofill.

Problems are becoming more of an assessment point than syntax.

Conclusion

As companies require more decision-making based on data analysis, SQL has become an increasingly valuable skill in today’s world.

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