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7-Day Token Retention

A medium SQL mock interview question on DataDriven. Practice with AI-powered feedback, real code execution, and a hire/no-hire decision.

Domain
SQL
Difficulty
medium
Seniority
senior

Interview Prompt

The developer platform team is worried about token churn and wants a quick retention curve. For each issuance date, they need two numbers side by side: how many tokens were active and generating traffic that day, and how many of those same owners still had an active, traffic-generating token 7 days later. Tokens with no expiration date should be treated as still valid. Limit the output to the first 7 dates chronologically.

How This Interview Works

  1. Read the vague prompt (just like a real interview)
  2. Ask clarifying questions to the AI interviewer
  3. Write your sql solution with real code execution
  4. Get instant feedback and a hire/no-hire decision