updating practice_queries

lab-3/music-store-app/sql/practice_queries.sql

@@ -67,3 +67,17 @@ VALUES
 
 /* 4. Delete a track */
 DELETE FROM Track WHERE album_upc='726517237627'; /* EXAMPLE */
+
+/* ------------------------------------ */
+
+/* 5. Retrieve details about an order
+Include the customer_id, delivery method
+and total order value in the result-set */
+
+SELECT Transaction.customer_id, Transaction.delivery, SUM(Album.price*LineItem.quantity) AS order_total /* notice use of aggregate function! */
+FROM Transaction 
+INNER JOIN LineItem 
+	ON Transaction.id=LineItem.trans_id 
+INNER JOIN Album 
+	ON Album.upc=LineItem.album_upc
+WHERE Transaction.id=1; /* EXAMPLE */