解法和前几题类似
需要注意的点

表连接时需要使用left join来左连结order_info表，因为client_id = 0这个数据在client表里是不存在的，会在连结时被去掉

select o.id, o.is_group_buy ,
case when o.is_group_buy = 'No'then c.name else NULL end
from order_info as o left join client as c
on o.client_id = c.id
where user_id in
(select user_id
from order_info
where date >'2025-10-15'
and product_name in ('C++','Java','Python')
and status = 'completed'
group by user_id
having count(id) > 1)
and o.date > '2025-10-15'
and o.product_name in ('C++','Java','Python')
and o.status = 'completed'
order by o.id asc