LeetCode题解

解题思路:

1.首先先求出每个用户首次订单表，将其命名为表t

 （select customer_id,min(order_date) as order_date
    from Delivery
    group by customer_id）as t

2.与原表连接，求出在用户首次订单表中即时订单的数量的总和

select sum(order_date = customer_pref_delivery_date) from
t,Delivery
where t.customer_id = Delivery.customer_id and t.order_date = Delivery.order_date

3.求出每个用户首次订单的数量

select distinct(customer_id) from Delivery

4.计算得到最终结果

完整SQL代码：

select round(sum(if(t.order_date = customer_pref_delivery_date,1,0))*100/(select count(*) from
(select distinct customer_id from Delivery) t1),2) as immediate_percentage
from (
    select customer_id,min(order_date) as order_date
    from Delivery
    group by customer_id
) t,Delivery
where t.customer_id = Delivery.customer_id and t.order_date = Delivery.order_date