题解 | #返回每个顾客不同订单的总金额#
返回每个顾客不同订单的总金额
https://www.nowcoder.com/practice/ce313253a81c4947b20e801cd4da7894
select cust_id,
sum(a.item_price*a.quantity) as total_ordered from
Orders b
left join OrderItems a on
b.order_num=a.order_num
group by b.cust_id
order by total_ordered desc
要搜的两个字段分别在不同的表则必须join
返回的id从多个变为没有重复则分组
