Update invoices-per-country.sql

invoices-per-country.sql

@@ -1,5 +1,13 @@
-SELECT co.country_name, count(*), AVG(i.total_price)
-FROM country co, city ci, customer cu, invoice i
-WHERE co.id = ci.country_id AND ci.id = cu.city_id AND cu.id = i.customer_id
-GROUP BY co.country name
-HAVING AVG(i.total_price) > (SELECT AVG(total price))
+SELECT 
+    c.country_name,
+    COUNT(i.id) AS total_invoices,
+    ROUND(AVG(i.total_price), 6) AS avg_invoice_amount
+FROM country c
+JOIN city ci ON ci.country_id = c.id
+JOIN customer cu ON cu.city_id = ci.id
+JOIN invoice i ON i.customer_id = cu.id
+GROUP BY c.country_name
+HAVING AVG(i.total_price) > (
+    SELECT AVG(total_price) 
+    FROM invoice
+);