About this solution: This solution is a good start, but it is missing some key details. For example, it does not mention how the system will handle concurrent changes or how it will deal with rollbacks. Additionally, the solution does not address how changes will be tracked if multiple users are making changes to the same database at the same time.

About this solution: The candidate's solution is correct and demonstrates a good understanding of SQL. The solution is also efficient, as it uses the GROUP BY clause to group the orders by customer, and then uses the COUNT() function to count the number of orders for each customer.