题解 | #牛客的课程订单分析(四)#

先将满足条件的UID选出来，然后根据uid选出最小日期，最后count出现的次数

SELECT user_id,min(date) as fisrt_buy_date,
count(case when product_name in("C++","Java","Python") then user_id else null end)as cnt
from order_info
where user_id in(
select user_id
from order_info
where `date`>"2025-10-15" and `status`="completed"
group by user_id
having count(case when product_name in("C++","Java","Python") then user_id else null end)>=2) and `date`>"2025-10-15" and `status`="completed"
GROUP by user_id
order by user_id