The Widest Net

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

Domain

SQL

Difficulty

medium

Seniority

L4

Problem

The ad analytics team wants each campaign's true reach: how many different registered users clicked at least one of its ads, counting a person once however many times they clicked. Keep campaigns that drew no clicks at all, and list the widest-reaching first.

Summary

Not the clicks. The crowd: how many people each campaign actually pulled in.

Practice This Problem

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