题解 | #牛客的课程订单分析(六)#

# 查询这些用户id的订单信息并连接client表以获得字段name
select t1.id, is_group_buy, name client_name
from (
    select id, is_group_buy, client_id
    from order_info
    where user_id in (
        # 先查询满足条件的用户id
        select user_id
        from order_info
        where datediff(`date`, '2025-10-15') > 0
        and status = 'completed'
        and product_name in ('C++', 'Java', 'Python')
        group by user_id
        having count(*) > 1
    )
    and datediff(`date`, '2025-10-15') > 0
    and status = 'completed'
    and product_name in ('C++', 'Java', 'Python')
) t1
join (
    select * from client
    union 
    select 0, Null
) t2
on t1.client_id = t2.id
order by t1.id;