🟡 Solve problem 1174

Author: AF2B

sql/1174.sql

@@ -0,0 +1,14 @@
+SELECT 
+    ROUND(
+        (SUM(CASE WHEN d1.order_date = d1.customer_pref_delivery_date THEN 1 ELSE 0 END) / COUNT(*)) * 100, 
+        2
+    ) AS immediate_percentage
+FROM 
+    Delivery d1
+JOIN 
+    (SELECT customer_id, MIN(order_date) AS first_order_date
+     FROM Delivery
+     GROUP BY customer_id) d2
+ON 
+    d1.customer_id = d2.customer_id
+    AND d1.order_date = d2.first_order_date;