Welcome to your interview.
The question is on your right: SQL for Top Categories by Revenue. Take a moment with it first.
Talk your thinking through with me if you like - when you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes). Discussion and graded submissions share your five interviewer interactions, so spend them well.
Given three tables (e.g., Customers, Orders, and Order Details), write a complex SQL query to find the top-performing product categories by revenue for a specific region.