题解 | 统计各等级会员用户下订单总额

select u.vip,ifnull(sum(order_price),0) order_total
from uservip_tb u 
left join order_tb o on u.user_id=o.user_id
group by u.vip
order by order_total desc;

！：left join和right join 的区别以及null-0