Crossed Signals

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

Domain

SQL

Difficulty

hard

Seniority

L5

Problem

Our ad platform and our ops alerting system share no common key, only a wall clock: line up each alert with the ad impressions that landed in the same hour. For each campaign, report how many alerts it drew and how many of those were marked resolved, most alerts first.

Summary

No shared key, only a shared clock.

Practice This Problem

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