甘肃网站建设专家,网站建设套路,多姿wordpress,xp系统做网站服务器在表 orders 中找到订单数最多客户对应的 customer_number 。
数据保证订单数最多的顾客恰好只有一位。
表 orders 定义如下#xff1a;
| Column | Type | |-------------------|-----------| | order_number (PK) | int | | customer_number | i…在表 orders 中找到订单数最多客户对应的 customer_number 。
数据保证订单数最多的顾客恰好只有一位。
表 orders 定义如下
| Column | Type | |-------------------|-----------| | order_number (PK) | int | | customer_number | int | | order_date | date | | required_date | date | | shipped_date | date | | status | char(15) | | comment | char(200) | 样例输入
| order_number | customer_number | order_date | required_date | shipped_date | status | comment | |--------------|-----------------|------------|---------------|--------------|--------|---------| | 1 | 1 | 2017-04-09 | 2017-04-13 | 2017-04-12 | Closed | | | 2 | 2 | 2017-04-15 | 2017-04-20 | 2017-04-18 | Closed | | | 3 | 3 | 2017-04-16 | 2017-04-25 | 2017-04-20 | Closed | | | 4 | 3 | 2017-04-18 | 2017-04-28 | 2017-04-25 | Closed | | 样例输出
| customer_number | |-----------------| | 3 | 解释
customer_number 为 3 的顾客有两个订单比顾客 1 或者 2 都要多因为他们只有一个订单 所以结果是该顾客的 customer_number 也就是 3 。 进阶 如果有多位顾客订单数并列最多你能找到他们所有的 customer_number 吗
思路:按人分组按数量排序取第一个。
select customer_number
from orders
group by customer_number
order by count(*) desc limit 1;
