Nested CTE insert

courses/course_postgres_mastery/26_nested_cte.sql

@@ -2,22 +2,16 @@
 Nested CTE
 */
 
---most valuable customers and their active addresses?
-
-
+--SQL 01
+--Most Valuable Customers
 SELECT
 c.customer_id,
 c.first_name,
 c.last_name,
 c.email,
-cn.country_name,
 cs.total_order_amount,
 cs.avg_order_amount
 FROM customer c
-INNER JOIN customer_address ca ON c.customer_id = ca.customer_id 
-INNER JOIN address a ON ca.address_id = a.address_id
-INNER JOIN address_status s ON ca.status_id = s.status_id
-INNER JOIN country cn ON a.country_id = cn.country_id 
 INNER JOIN (
 	--customer ID and their stats
 	SELECT
@@ -36,11 +30,18 @@ INNER JOIN (
 	) o
 	GROUP BY o.customer_id
 ) cs ON c.customer_id = cs.customer_id
-WHERE s.address_status = 'Active'
 ORDER BY cs.total_order_amount DESC;
 
-
---without addresses
+--SQL 02
+WITH order_value AS (
+	SELECT
+	co.customer_id,
+	co.order_id,
+	SUM(ol.price) AS order_amount
+	FROM cust_order co 
+	INNER JOIN order_line ol ON co.order_id = ol.order_id
+	GROUP BY co.customer_id, co.order_id
+)
 SELECT
 c.customer_id,
 c.first_name,
@@ -55,16 +56,37 @@ INNER JOIN (
 	o.customer_id,
 	SUM(o.order_amount) AS total_order_amount,
 	ROUND(AVG(o.order_amount), 2) AS avg_order_amount
-	FROM (
-		--order amounts
-		SELECT
-		co.customer_id,
-		co.order_id,
-		SUM(ol.price) AS order_amount
-		FROM cust_order co 
-		INNER JOIN order_line ol ON co.order_id = ol.order_id
-		GROUP BY co.customer_id, co.order_id
-	) o
+	FROM order_value o
 	GROUP BY o.customer_id
 ) cs ON c.customer_id = cs.customer_id
 ORDER BY cs.total_order_amount DESC;
+
+
+--SQL 03
+WITH order_value AS (
+	SELECT
+	co.customer_id,
+	co.order_id,
+	SUM(ol.price) AS order_amount
+	FROM cust_order co 
+	INNER JOIN order_line ol ON co.order_id = ol.order_id
+	GROUP BY co.customer_id, co.order_id
+),
+customer_order_stats AS (
+	SELECT
+	o.customer_id,
+	SUM(o.order_amount) AS total_order_amount,
+	ROUND(AVG(o.order_amount), 2) AS avg_order_amount
+	FROM order_value o
+	GROUP BY o.customer_id
+)
+SELECT
+c.customer_id,
+c.first_name,
+c.last_name,
+c.email,
+cs.total_order_amount,
+cs.avg_order_amount
+FROM customer c
+INNER JOIN customer_order_stats cs ON c.customer_id = cs.customer_id
+ORDER BY cs.total_order_amount DESC;