The Holdouts

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

Domain

SQL

Difficulty

medium

Seniority

L5

Problem

In our push-notification log, each message records the plan tier it targeted in the `platform` field. Find the unique users who were sent a `basic`-tier notification but never a `premium`-tier one.

Summary

Subscribed. But never upgraded.

Practice This Problem

Solve this SQL problem with real code execution. DataDriven runs your SQL queries against a real database and grades it automatically.