SQL Interview Questions

1️⃣6️⃣ What is the difference between INNER JOIN and LEFT JOIN?
1️⃣7️⃣ How do you filter unique records from a table?
1️⃣8️⃣ What is the purpose of GROUP BY in SQL?
1️⃣9️⃣ Explain the difference between HAVING and WHERE clauses.
2️⃣0️⃣ How do you retrieve the second-highest salary from a table?
2️⃣1️⃣ What is a CTE (Common Table Expression) and why is it used?
2️⃣2️⃣ How do you remove duplicate rows from a SQL table?
2️⃣3️⃣ Explain window functions like RANK(), DENSE_RANK(), and ROW_NUMBER().
2️⃣4️⃣ How do you optimize SQL queries for better performance?
2️⃣5️⃣ What is indexing, and how does it improve query speed?
2️⃣6️⃣ How do you write an efficient stored procedure in SQL?
2️⃣7️⃣ What is partitioning, and how does it work in large datasets?
2️⃣8️⃣ How would you write a SQL query to pivot and unpivot data?
2️⃣9️⃣ What are recursive queries, and when would you use them?
3️⃣0️⃣ How do you implement slowly changing dimensions (SCD) in SQL?

Source: Ghansham Badgujar LinkedIn Profile