Table: Delivery
+-----------------------------+---------+ +| Column Name | Type | ++-----------------------------+---------+ +| delivery_id | int | +| customer_id | int | +| order_date | date | +| customer_pref_delivery_date | date | ++-----------------------------+---------+ +delivery_id is the column of unique values of this table. +The table holds information about food delivery to customers that make orders at some date and specify a preferred delivery date (on the same order date or after it). ++ +
+ +
If the customer's preferred delivery date is the same as the order date, then the order is called immediate; otherwise, it is called scheduled.
+ +The first order of a customer is the order with the earliest order date that the customer made. It is guaranteed that a customer has precisely one first order.
+ +Write a solution to find the percentage of immediate orders in the first orders of all customers, rounded to 2 decimal places.
+ +The result format is in the following example.
+ ++
Example 1:
+ +Input: +Delivery table: ++-------------+-------------+------------+-----------------------------+ +| delivery_id | customer_id | order_date | customer_pref_delivery_date | ++-------------+-------------+------------+-----------------------------+ +| 1 | 1 | 2019-08-01 | 2019-08-02 | +| 2 | 2 | 2019-08-02 | 2019-08-02 | +| 3 | 1 | 2019-08-11 | 2019-08-12 | +| 4 | 3 | 2019-08-24 | 2019-08-24 | +| 5 | 3 | 2019-08-21 | 2019-08-22 | +| 6 | 2 | 2019-08-11 | 2019-08-13 | +| 7 | 4 | 2019-08-09 | 2019-08-09 | ++-------------+-------------+------------+-----------------------------+ +Output: ++----------------------+ +| immediate_percentage | ++----------------------+ +| 50.00 | ++----------------------+ +Explanation: +The customer id 1 has a first order with delivery id 1 and it is scheduled. +The customer id 2 has a first order with delivery id 2 and it is immediate. +The customer id 3 has a first order with delivery id 5 and it is scheduled. +The customer id 4 has a first order with delivery id 7 and it is immediate. +Hence, half the customers have immediate first orders. ++