For each user, show their username and the total number of distinct product categories they have pur

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

Domain

SQL

Difficulty

medium

Problem

For each user, show their username and the total number of distinct product categories they have purchased, counting NULL as a separate category if present.

Practice This Problem

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