题解 | #牛客的课程订单分析(四)#

select a.user_id, b.min as first_buy_date, a.sum as cnt
from (
    select user_id, count(id) as sum from order_info
    where date >= '2025-10-15' and status = 'completed'
    and product_name in ('Java', 'Python', 'C++')
    group by user_id
) a
join (
    select user_id, min(date) as min from order_info
    where date >= '2025-10-15' and status = 'completed' 
    and product_name in ('Java', 'Python', 'C++')
    group by user_id
) b
on a.user_id = b.user_id
where a.sum >= 2
order by a.user_id asc