题解 | #牛客的课程订单分析(五)#

select
    user_id,
    min(date) as first_buy_date,
    max(date) as second_buy_date,
    cnt
from (
    select
        user_id,
        date,
        dense_rank() over (partition by user_id order by date) as r_d,
        count(user_id) over (partition by user_id) as cnt
    from order_info
    where
        date > '2025-10-15' AND
        status = 'completed' AND
        product_name IN ('C++','Java','Python')
) as t
where
    r_d <=2 AND
    cnt >=2
group by user_id