题解 | 查询订单

select
        od.order_id,
        c.customer_name,
        max_order_date as order_date
from (
    select
        customer_id,
        max(order_date) as max_order_date
    from 
            orders
    group by 
            customer_id
)a
inner join 
        orders as od
on 
        a.customer_id = od.customer_id
and 
        a.max_order_date = od.order_date
inner join 
        customers as c
on 
        c.customer_id = a.customer_id
order by 
        customer_name