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

Domain

SQL

Difficulty

medium

Seniority

L4

Problem

Build a notification volume breakdown pivoted by platform and day of week, scoped to users enrolled in at least one experiment. Rows should be days of the week (0=Sunday through 6=Saturday), with separate count columns for ios, android, and web. Return the day of week and each platform's count.

Summary

Notifications by platform and day. When does the audience actually show up?

Practice This Problem

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