题解 | #牛客的课程订单分析(五)#

with a as (select user_id,date,
        row_number() over (partition by user_id order by date) as rn,
        count(*) over (partition by user_id) as cnt
        from order_info
        where status = 'completed'
        and date > '2025-10-15'
        and product_name in ('C++','Java','Python'))
select user_id,
       min(date) as first_buy_date,
       max(date) as second_buy_date,
       cnt
from a
where cnt >= 2 and rn <= 2
group by user_id,cnt
order by user_id;