题解 | #牛客的课程订单分析(七)#
牛客的课程订单分析(七)
http://www.nowcoder.com/practice/d6f4a37f966145da8900ba9edcc4c068
知识点
- 窗口函数建立新表，主要是筛选出订单数量大于等于2的记录
- 左连接客户端表，使用ifnull函数，如果有客户端名称就取出现null值就是groupby，按照source进行分组，最后计数客户端出现次数
代码
select ifnull(c.name, 'GroupBuy') as source,
count(*) as cnt
from (
select *, count(*) over (partition by user_id) as r
from order_info
where date > '2025-10-15'
and product_name in ('C++', 'Python', 'Java')
and status = 'completed'
) as t
left join client as c
on c.id = t.client_id
where t.r >= 2
group by source
order by source
