题解 | #牛客的课程订单分析(四)#

mysql套中套，挺突然的解法：
select s.user_id,t.yy,t.gg from order_info s,
(
select user_id,min(date) yy,count(*) gg from order_info
where product_name in ('C++','Java','Python')
and date>'2025-10-15' and status = 'completed'
group by user_id) t
where s.user_id = t.user_id
and product_name in ('C++','Java','Python')
and date>'2025-10-15'
and status = 'completed'
and t.gg>=2
group by s.user_id,t.yy,t.gg
order by s.user_id