Lab done

joins_lab.sql

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+USE sakila;
+
+#1
+SELECT 
+    c.name AS category,
+    COUNT(fc.film_id) AS number_of_films
+FROM category c
+JOIN film_category fc ON c.category_id = fc.category_id
+GROUP BY c.name;
+
+#2
+SELECT 
+    s.store_id,
+    ci.city,
+    co.country
+FROM store s
+JOIN address a ON s.address_id = a.address_id
+JOIN city ci ON a.city_id = ci.city_id
+JOIN country co ON ci.country_id = co.country_id;
+
+#3
+SELECT 
+    s.store_id,
+    SUM(p.amount) AS total_revenue
+FROM store s
+JOIN staff st ON s.store_id = st.store_id
+JOIN payment p ON st.staff_id = p.staff_id
+GROUP BY s.store_id;
+
+#4
+SELECT 
+    c.name AS category,
+    ROUND(AVG(f.length), 2) AS avg_running_time
+FROM category c
+JOIN film_category fc ON c.category_id = fc.category_id
+JOIN film f ON fc.film_id = f.film_id
+GROUP BY c.name;
+
+#5
+SELECT 
+    c.name AS category,
+    ROUND(AVG(f.length), 2) AS avg_running_time
+FROM category c
+JOIN film_category fc ON c.category_id = fc.category_id
+JOIN film f ON fc.film_id = f.film_id
+GROUP BY c.name
+ORDER BY avg_running_time DESC
+LIMIT 1;
+
+#6
+SELECT 
+    f.title,
+    COUNT(r.rental_id) AS rental_count
+FROM film f
+JOIN inventory i ON f.film_id = i.film_id
+JOIN rental r ON i.inventory_id = r.inventory_id
+GROUP BY f.title
+ORDER BY rental_count DESC
+LIMIT 10;
+
+#7
+SELECT 
+    f.title,
+    s.store_id,
+    COUNT(i.inventory_id) AS available_copies
+FROM film f
+JOIN inventory i ON f.film_id = i.film_id
+JOIN store s ON i.store_id = s.store_id
+WHERE f.title = 'Academy Dinosaur' AND s.store_id = 1
+GROUP BY f.title, s.store_id;
+
+#8
+SELECT 
+    f.title,
+    CASE 
+        WHEN IFNULL(MAX(i.inventory_id), 0) = 0 THEN 'NOT available'
+        ELSE 'Available'
+    END AS availability_status
+FROM film f
+LEFT JOIN inventory i ON f.film_id = i.film_id
+GROUP BY f.title;