Customer Placing the Largest Number of Orders - Problem
You are given a table Orders that contains information about orders and their corresponding customers.
Write a SQL solution to find the customer_number for the customer who has placed the largest number of orders.
The test cases are generated so that exactly one customer will have placed more orders than any other customer.
Table Schema
Orders
| Column Name | Type | Description |
|---|---|---|
order_number
PK
|
int | Primary key - unique identifier for each order |
customer_number
|
int | Customer identifier who placed the order |
Primary Key: order_number
Note: Each row represents one order placed by a customer
Input & Output
Example 1 — Basic Case
Input Table:
| order_number | customer_number |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 3 |
Output:
| customer_number |
|---|
| 3 |
💡 Note:
Customer 3 has placed 2 orders (order_number 3 and 4), while customers 1 and 2 have each placed only 1 order. Therefore, customer 3 is returned as the customer with the largest number of orders.
Example 2 — Single Customer Dominant
Input Table:
| order_number | customer_number |
|---|---|
| 1 | 5 |
| 2 | 5 |
| 3 | 5 |
| 4 | 1 |
| 5 | 2 |
Output:
| customer_number |
|---|
| 5 |
💡 Note:
Customer 5 has placed 3 orders, which is more than any other customer. Customer 1 and 2 have each placed only 1 order, making customer 5 the clear winner.
Constraints
-
1 ≤ order_number ≤ 500 -
1 ≤ customer_number ≤ 500 -
All
order_numberare unique - Exactly one customer will have the most orders
Visualization
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Understanding the Visualization
1
Input
Orders table with order and customer data
2
Group & Count
GROUP BY customer_number and COUNT(*)
3
Find Max
ORDER BY count DESC, LIMIT 1
Key Takeaway
🎯 Key Insight: Use GROUP BY with aggregate functions to analyze patterns in relational data
💡
Explanation
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// Output will appear here after running code