【LeetCode-SQL586】訂單最多的客戶（基礎題，求衆數，可能多個）

文章目錄

• ​​一、題目​​
• ​​二、思路​​
• ​​三、代碼​​
• ​​Reference​​

一、題目

已知order表：

二、思路

如果最多訂單數隻有一個客戶，那就可以直接粗暴的分組後計算每組個數，然後排序求第一個。

SELECT customer_number
FROM orders
GROUP BY customer_number
ORDER BY COUNT(*) DESC
LIMIT 1;      

但如果是有并列客戶同時最多訂單數，則先找出最大訂單數的數值，然後用​

​Having​

​子查詢求衆數。

三、代碼

# Write your MySQL query statement below
SELECT customer_number
FROM orders
GROUP BY customer_number
HAVING COUNT(*) >= (
    SELECT COUNT(*) AS cnt
    FROM orders
    GROUP BY customer_number
    ORDER BY cnt DESC
    LIMIT 1
);      

Reference

[1] ​​SQL執行個體：求衆數​​​