LeetCode（数据库）- 订单最多的客户

题目链接：​​点击打开链接​​

题目大意：略。

解题思路：解决方案(2)比解决方案(1)更优雅，是因为对 ORDER BY 和 GROUP BY 的理解执行顺序没到位。

AC 代码

-- 解决方案(1)
SELECT customer_number
FROM (SELECT customer_number, COUNT(customer_number) cnt 
FROM orders
GROUP BY customer_number) RS
ORDER BY cnt DESC
LIMIT 1;

-- 解决方案(2)
SELECT
    customer_number
FROM
    orders
GROUP BY customer_number
ORDER BY COUNT(*) DESC
LIMIT 1;