1.2025-10-15之后，同一个用户下单状态为购买成功的C++，java，python的订单信息

# SELECT * 
# FROM order_info
# WHERE status = "completed"
# and product_name IN ("C++", "Java", "Python")
# and date > '2025-10-15'

2.在2025-10-15以后，同一个用户下单2个以及2个以上状态为

购买成功的C++课程或Java课程或Python课程的user_id

# select user_id
# from order_info
# where date > '2025-10-15'
# and product_name in ('C++', 'Python', 'Java')
# and status = 'completed'
# group by user_id
# having count(*) > 1

3.用子查询将1和2连接起来，最后用id排序

select T.*
from (
    select *
    from order_info
    where date > '2025-10-15'
    and product_name in ('C++', 'Python', 'Java')
    and status = 'completed'
    ) T
where user_id in (
    select user_id
    from order_info
    where date > '2025-10-15'
    and product_name in ('C++', 'Python', 'Java')
    and status = 'completed'
    group by user_id
    having count(*) > 1
    )
order by id