Solved lab

lab-sql-joins.sql

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+SELECT 
+    c.name AS category_name, 
+    COUNT(fc.film_id) AS number_of_films
+FROM 
+    sakila.category c
+JOIN 
+    sakila.film_category fc ON c.category_id = fc.category_id
+JOIN 
+    sakila.film f ON fc.film_id = f.film_id
+GROUP BY 
+    c.name;
+
+    SELECT 
+    s.store_id, 
+    ci.city, 
+    co.country 
+FROM 
+    sakila.store s
+JOIN 
+    sakila.address a ON s.address_id = a.address_id
+JOIN 
+    sakila.city ci ON a.city_id = ci.city_id
+JOIN 
+    sakila.country co ON ci.country_id = co.country_id;
+
+    SELECT 
+    s.store_id, 
+    SUM(p.amount) AS total_revenue
+FROM 
+    sakila.payment p
+JOIN 
+    sakila.rental r ON p.rental_id = r.rental_id
+JOIN 
+    sakila.inventory i ON r.inventory_id = i.inventory_id
+JOIN 
+    sakila.store s ON i.store_id = s.store_id
+GROUP BY 
+    s.store_id;
+
+    SELECT 
+    c.name AS category_name,
+    AVG(f.length) AS avg_running_time
+FROM 
+    sakila.category c
+JOIN 
+    sakila.film_category fc ON c.category_id = fc.category_id
+JOIN 
+    sakila.film f ON fc.film_id = f.film_id
+GROUP BY 
+    c.name;