7-Day Token Retention

A medium SQL interview practice problem on DataDriven. Write and execute real sql code with instant grading.

Domain

SQL

Difficulty

medium

Seniority

senior

Problem

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.

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