思路：
1.先找出符合条件的user_id
select user_id from order_info
where date > "2025-10-15"
and status = "completed"
and product_name in ("C++","Java","Python")
GROUP by user_id
having COUNT(id) > 1

2.从order_info表中获取这些user_id所有信息
SELECT * from order_info
WHERE user_id in (
select user_id from order_info
where date > "2025-10-15"
and status = "completed"
and product_name in ("C++","Java","Python")
GROUP by user_id
having COUNT(id) > 1 )
and date > "2025-10-15"
and status = "completed"
and product_name in ("C++","Java","Python")
order by id