SQL Interview Questions & Assessment
Evaluate SQL proficiency including complex queries, joins, indexing, query optimization, and database design principles.
Why SQL Matters
SQL is a foundational skill for any developer working with data. Every backend engineer, data analyst, and data scientist needs strong SQL skills.
Sample Interview Questions
Explain the difference between INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN.
How would you optimize a slow query? Walk through your debugging process.
What are window functions? Write a query using ROW_NUMBER, RANK, and LAG.
Explain normalization. What are the trade-offs between normalization and denormalization?
Design a schema for a social media platform. Explain your indexing strategy.
How to Prepare
Master JOINs, subqueries, CTEs, and window functions
Understand indexing: B-tree vs hash, composite indexes, covering indexes
Practice reading and optimizing EXPLAIN plans
Know the differences between major SQL databases
Practice schema design with real-world scenarios
Related Skills
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