题解 | 牛客的课程订单分析(四)

with
    t as (
        select
            *,
            count(*) over (partition by user_id) cnt,
            rank() over(partition by user_id order by date)r
        from
            order_info
        where
            date > '2025-10-15'
            and status = 'completed'
            and (
                product_name = 'C++'
                or product_name = 'Python'
                or product_name = 'Java'
            )
    )
select user_id, date as first_buy_date,cnt
from t
where r = 1 and cnt > 1