sql21（Leetcode1174即时食物配送2）

代码：

# Write your MySQL query statement below

select round (
    sum(order_date = customer_pref_delivery_date) * 100 /
    count(*),
    2
) as immediate_percentage
from Delivery
where (customer_id, order_date) in (
    select customer_id, min(order_date)
    from delivery
    group by customer_id
)