题解 | #牛客的课程订单分析(七)#

select (case when name is null then 'GroupBuy' else name end) source,count(id)cnt from
(select o.id id,is_group_buy,name,count(o.id)over(partition by user_id) cu
from order_info o left join client c on o.client_id=c.id where date>'2025-10-15' and status='completed' 
and product_name in('C++','Java','Python'))t1 where cu>1
group by source
order by source

也可以用ifnull函数，ifnull(name, 'GroupBuy')