9. Highest Order Placing Customer
As a business, you want to identify which customer places the most orders. This is useful for targeting high-value customers with loyalty programs or marketing campaigns.
You are given a table named Orders that tracks customer orders.
╔═════════════════╦══════════╗ ║ Column Name ║ Type ║ ╠═════════════════╬══════════╣ ║ order_number ║ int ║ ║─────────────────┼──────────║ ║ customer_number ║ int ║ ╚═════════════════╩══════════╝
- order_number: Unique order ID (Primary Key) for each order placed.
- customer_number: ID of the customer who placed the order.
Write a query to find the customer_number of the customer who has placed the most orders. It is guaranteed that exactly one customer will have placed more orders than any other.
Example 1:
Example:
Input:
Orders Table
╔══════════════╦═════════════════╗ ║ order_number ║ customer_number ║ ╠══════════════╬═════════════════╣ ║ 1 ║ 1 ║ ║──────────────┼─────────────────║ ║ 2 ║ 2 ║ ║──────────────┼─────────────────║ ║ 3 ║ 3 ║ ║──────────────┼─────────────────║ ║ 4 ║ 3 ║ ╚══════════════╩═════════════════╝
Expected Output:
╔═════════════════╗ ║ customer_number ║ ╠═════════════════╣ ║ 3 ║ ╚═════════════════╝
Explanation:
- Customer 1 placed 1 order.
- Customer 2 placed 1 order.
- Customer 3 placed 2 orders (most orders).
Thus, the result is customer_number 3.
Still unsure what the problem is asking ?
Let’s go through a few more examples, step by step, to make it clearer.