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

Domain

SQL

Difficulty

hard

Seniority

L5

Problem

For December 2025 and January 2026, find the percentage of users active in a given month who also appear in any future month. Treat missing future activity as zero retention. Return the service name, month, and retention percentage.

Summary

Users came back. Or they did not.

Practice This Problem

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