The Ninety-Day Comeback
A hard SQL mock interview question on DataDriven, with an AI interviewer who asks follow-up questions and a hire or no-hire decision at the end.
- Domain
- SQL
- Difficulty
- hard
- Seniority
- L4
Interview Prompt
A user counts as retained if they come back for another session within 90 days of their first one. Working from the user_sessions table, return the overall retention rate: the share of all users with any session who were retained.
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 and run your SQL against a real database
- Answer the interviewer's follow-up questions, then get a hire or no-hire decision