Top 20 Topics for Sr. Developer | SQL Interview | DATABASE interview

Certainly! Here are some intermediate to advanced SQL interview questions suitable for developers with 5 to 8 years of experience:

1. Normalization: Explain the concept of database normalization and its different forms (1NF, 2NF, 3NF).

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2. Indexes: What are database indexes, and how do they improve query performance? Can you explain the differences between clustered and non-clustered indexes?

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3. Joins: Discuss the various types of SQL joins (INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN). When would you use each type, and what are the potential pitfalls?

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4. Subqueries: What is a subquery, and how is it different from a JOIN operation? Provide an example of a situation where a subquery is more appropriate than a JOIN.

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5. Performance Optimization: Describe some strategies for optimizing SQL queries and improving database performance.

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6. Transactions: What is a database transaction? Explain the ACID properties of transactions and how they ensure data integrity.

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7. Views: What is a database view, and why might you use it? Can a view be indexed, and if so, why would you do that?

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8. Stored Procedures vs. Functions: Compare and contrast stored procedures and functions in SQL. When would you use one over the other?

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9. Concurrency Control: How does a database handle concurrent transactions? Discuss techniques like locking and optimistic concurrency control.

10. Indexing Strategies: Explain when and how you would use composite indexes. What are covering indexes, and how do they impact query performance?

11. Normalization vs. Denormalization: When is it appropriate to denormalize a database, and what are the potential advantages and disadvantages?

12. Database Security: What are some best practices for securing a SQL database, and what roles and permissions are commonly used to control access?

13. SQL Injection: What is SQL injection, and how can it be prevented or mitigated in database applications?

14. Window Functions: Explain window functions in SQL. Provide an example of how you would use them in a query.

15. NoSQL vs. SQL: Compare SQL databases with NoSQL databases. In what scenarios would you choose one over the other?

16. Database Design: Describe your approach to database schema design. What factors do you consider when designing a database schema?

17. Backup and Recovery: What are the best practices for database backup and recovery? How would you handle a critical data loss situation?

18. ETL Processes: What is ETL (Extract, Transform, Load), and how does it relate to databases? Describe a situation where you implemented an ETL process.

19. Database Sharding: Explain the concept of database sharding and when it is appropriate to use it for scaling a database system.

20. Query Optimization: Given a complex SQL query, walk through the steps you would take to optimize it for better performance.

These questions cover a range of SQL topics and should help you assess a candidate's depth of knowledge and experience with SQL databases. You can tailor the questions to the specific needs of your interview and organization.