题解 | #牛客的课程订单分析(七)#

select
    if (c.name is NULL, 'GroupBuy', c.name) source,
    count(*) cnt
from
    (
        select
            *,
            count(*) over (
                partition by
                    user_id
            ) as ocnt
        from
            order_info
        where
            date > '2025-10-15'
            and status = 'completed'
            and product_name in ('C++', 'Java', 'Python')
    ) o
    left join client c on o.client_id = c.id
where
    ocnt > 1
group by
    source
order by
    source;