select t1.vip, 
     #把null替换为0
    if(t1.order_total is null, 0, t1.order_total) as order_total
from (select vip,
             sum(order_price) order_total
      from uservip_tb ut
               left join order_tb ot
                         using (user_id)
      group by vip
      order by order_total desc) as t1