The Ninety-Day Comeback
A hard SQL mock interview question on DataDriven. Practice with AI-powered feedback, real code execution, and a hire/no-hire decision.
- Domain
- SQL
- Difficulty
- hard
- Seniority
- L4
Interview Prompt
We run a web product and want to measure early retention. From the user_sessions table, treat each user's earliest session as their first, and call a user retained if they start another session after that first one. Return a single retention rate as a REAL value: retained users divided by everyone who ever had a session.
Summary
Everyone shows up once. Who comes back before the quarter ends?
How This Interview Works
- Read the vague prompt (just like a real interview)
- Ask clarifying questions to the AI interviewer
- Write your sql solution with real code execution
- Get instant feedback and a hire/no-hire decision