题解 | 牛客的课程订单分析(五)

select
    user_id,first_buy_date,second_buy_date,cnt
from
    (select
         user_id,
         min(date) over(partition by user_id) as first_buy_date,
         lead(date,1,0) over(partition by user_id order by date) as second_buy_date,
         count(*) over(partition by user_id) as cnt,
         date
    from order_info
    where date>='2025-10-16'
      and status='completed'
      and product_name in('C++','Java','Python')
    ) a
where a.cnt>=2 and date=first_buy_date
order by a.user_id ;