LeetCode MySQL-586. Customer Placing the Largest Number of Orders

    AllenLi
    LeetCode MySQL

    Write an SQL query to find the customer_number for the customer who has placed the largest number of orders.

    寫一個 SQL Query來尋找下單訂單數量最多的客戶。

    Table: Orders

    +-----------------+----------+
| Column Name     | Type     |
+-----------------+----------+
| order_number    | int      |
| customer_number | int      |
+-----------------+----------+
order_number is the primary key for this table.
This table contains information about the order ID and the customer ID.

    Example 1:

    Input: 
Orders table:
+--------------+-----------------+
| order_number | customer_number |
+--------------+-----------------+
| 1            | 1               |
| 2            | 2               |
| 3            | 3               |
| 4            | 3               |
+--------------+-----------------+
Output: 
+-----------------+
| customer_number |
+-----------------+
| 3               |
+-----------------+
Explanation: 
The customer with number 3 has two orders, which is greater than either customer 1 or 2 because each of them only has one order. 
So the result is customer_number 3.

    Solution:
    1. 選擇標題 customer_number。
    2. 來自 Orders 的 table。
    3. 以 customer_number 為群組。
    4. 以 customer_number 的次數做降冪排序。
    5. 取該排列的第一個順位。

    Code1:

    SELECT 
	customer_number
	FROM Orders
GROUP BY customer_number
ORDER BY COUNT(customer_number) DESC
LIMIT 1 OFFSET 0;

    newOrderss

    Related Posts