The Notification Lifecycle

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

Domain

SQL

Difficulty

medium

Seniority

L4

Problem

Our push notification system records a delivery status for every message, but that status is entered inconsistently, so the same outcome shows up in different letter cases. For each registered user, count how many of their notifications were delivered, how many were opened, and how many failed, where an open is captured by its own flag rather than the status text.

Summary

Sent, opened, ignored. What happened after the alert went out?

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