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

L5

Problem

The developer platform team wants a 7-day token retention curve. A token counts as ACTIVE-WITH-TRAFFIC when its status is 'active' (compare it case-insensitively, since the data mixes 'active' and 'Active') and its requests value is greater than 0. A token with no expiration date is treated as still valid. For each issuance date, report two numbers side by side: how many distinct owners had an active-with-traffic token issued that day (active_day0), and how many of those same owners still held an active-with-traffic token that was valid as of 7 days after that date, i.e. issued on or before issued+7 and not expired before issued+7 (active_day7). Order by the issuance date and return only the first 7 dates.

Summary

Premium tokens, day by day.

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