task: #1174

Author: Ivanbyone

README.md

@@ -79,6 +79,7 @@ Have a good contributing!
     - [1045. Customers Who Bought All Products](./leetcode/medium/1045.%20Customers%20Who%20Bought%20All%20Products.sql)
     - [1070. Product Sales Analysis III](./leetcode/medium/1070.%20Product%20Sales%20Analysis%203.sql)
     - [1158. Market Analysis 1](./leetcode/medium/1158.%20Market%20Analysis%201.sql)
+    - [1174. Immediate Food Delivery II](./leetcode/medium/1174.%20Immediate%20Food%20Delivery%20II.sql)
     - [1193. Monthly Transactions I](./leetcode/medium/1193.%20Monthly%20Transactions%20I.sql)
     - [1341. Movie Rating](./leetcode/medium/1341.%20Movie%20Rating.sql)
     - [1907. Count Salary Categories](./leetcode/medium/1907.%20Count%20Salary%20Categories.sql)

leetcode/medium/1174. Immediate Food Delivery II.sql

@@ -0,0 +1,47 @@
+/*
+Question 1174. Immediate Food Delivery II
+Link: https://leetcode.com/problems/immediate-food-delivery-ii/description/?envType=study-plan-v2&envId=top-sql-50
+
+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.
+*/
+
+WITH first_delivery AS (
+    SELECT 
+        customer_id,
+        MIN(order_date) AS first_order_date
+    FROM Delivery
+    GROUP BY customer_id
+)
+
+SELECT
+    ROUND(COUNT(
+        CASE
+            WHEN d.customer_pref_delivery_date = f.first_order_date
+                THEN 1
+        END
+    ) * 100.00 / COUNT(1), 2) AS immediate_percentage
+FROM Delivery AS d
+LEFT JOIN 
+    first_delivery AS f
+    ON
+        d.customer_id = f.customer_id
+        AND d.order_date = f.first_order_date
+WHERE f.first_order_date IS NOT NULL