Stop guessing.
Start knowing.

Everything you need to master SQL interview questions in one place: a roadmap, reference guides, concept questions, and practice problems.

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Roadmap

Know what to study next.

The SQL roadmap sequences every topic from first principles to advanced. Follow the path or jump to what you need.

SQL roadmap →
Beginner
Your First SELECT
Filtering with WHERE
JOINs: Combining Tables
Intermediate
Window Functions
CTEs
Subqueries
Advanced
Recursive CTEs
Query Planning & EXPLAIN
Performance Tuning

Given this table (orders):

idamount
1100
2NULL
3200

What does this return?

SELECT COUNT(amount) FROM orders;

Learn

Test what you actually know.

Concept questions on NULL handling, window functions, joins, and aggregation edge cases — the things most people have wrong without knowing it. Each topic has a reference guide that explains the behavior, not just the rule.

SQL concept questions →Browse reference guides →

Practice

Real problems. Real feedback.

152+ SQL problems from actual company interviews, run against a live database, not a mock. Step-by-step hints if you're stuck. Written solutions with complexity analysis when you're done.

SQL problems →
top-customers.sql
SELECT
customer_id,
SUM(amount) AS total_spent
FROM orders
GROUP BY customer_id
ORDER BY total_spent DESC
LIMIT 10
AmazonGoogleMetaStripeAirbnbMicrosoftUberLinkedInSpotifyDoorDashShopifyXand more

Companies

Practice for the job you want.

Every problem is tagged to the company that asked it. Filter by Amazon, Google, Meta, Stripe, Airbnb, and more.

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Start with the roadmap.

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