题解 | #牛客的课程订单分析(四)#

select user_id, min(date) first_buy_date, count(*) cnt
from order_info
where datediff(date,'2025-10-15')>0
and product_name in ('C++','Java','Python')
and status='completed'
group by user_id
having cnt>1
order by user_id

• 考察聚合函数的使用