From 0ad0f881cd1574f2112e8dd0207c3fca398d9f41 Mon Sep 17 00:00:00 2001
From: GarriguesElena <garrigueselena@gmail.com>
Date: Wed, 8 Jul 2026 15:53:46 +0200
Subject: [PATCH] sql_joins_lab_solved

sql_joins_lab_solved
---
 SQL_joins_lab.sql | 82 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 SQL_joins_lab.sql

diff --git a/SQL_joins_lab.sql b/SQL_joins_lab.sql
new file mode 100644
index 0000000..0b3f7d2
--- /dev/null
+++ b/SQL_joins_lab.sql
@@ -0,0 +1,82 @@
+USE sakila;
+
+-- 1. List the number of films per category.
+SELECT COUNT(f.film_id) AS number_of_films, c.name AS category
+FROM film AS f
+JOIN film_category AS fc
+ON f.film_id = fc.film_id
+JOIN category AS c
+ON fc.category_id = c.category_id
+GROUP BY c.name;
+
+
+-- 2. Retrieve the store ID, city, and country for each store.
+SELECT s.store_id AS store, c.city, co.country
+FROM store AS s
+JOIN address AS a
+ON s.address_id = a.address_id
+JOIN city as c
+ON a.city_id = c.city_id
+JOIN country AS co
+ON c.country_id = co.country_id;
+
+
+-- 3. Calculate the total revenue generated by each store in dollars.
+SELECT s.store_id AS store, SUM(p.amount) AS total_revenue
+FROM store AS s
+JOIN staff AS st
+ON s.store_id = st.store_id
+JOIN payment AS p
+ON st.staff_id = p.staff_id
+GROUP BY store;
+
+
+-- 4. Determine the average running time of films for each category.
+SELECT ROUND(AVG(f.length), 2) AS average_running_time, c.name AS category 
+FROM film AS f
+JOIN film_category AS fc
+ON f.film_id = fc.film_id
+JOIN category AS c
+ON fc.category_id = c.category_id
+GROUP BY c.name;
+
+-- 5. Identify the film categories with the longest average running time.
+SELECT ROUND(AVG(f.length), 2) AS average_running_time, c.name AS category 
+FROM film AS f
+JOIN film_category AS fc
+ON f.film_id = fc.film_id
+JOIN category AS c
+ON fc.category_id = c.category_id
+GROUP BY c.name
+ORDER BY average_running_time DESC;
+
+
+-- 6. Display the top 10 most frequently rented movies in descending order.
+SELECT f.title AS movie, COUNT(r.rental_id) AS times_rented
+FROM film AS f
+JOIN inventory AS i
+ON f.film_id = i.film_id
+JOIN rental AS r
+ON i.inventory_id = r.inventory_id
+GROUP BY movie
+ORDER BY times_rented DESC
+LIMIT 10;
+
+
+-- 7. Determine if "Academy Dinosaur" can be rented from Store 1.
+SELECT f.title, i.store_id 
+FROM film AS f
+JOIN inventory AS i
+ON f.film_id = i.film_id
+WHERE f.title = "Academy Dinosaur" AND i.store_id = 1;
+
+-- 8. Provide a list of all distinct film titles, along with their availability status in the inventory. Include a column indicating whether each title is 'Available' or 'NOT available.' Note that there are 42 titles that are not in the inventory, and this information can be obtained using a CASE statement combined with IFNULL."
+SELECT DISTINCT f.title,
+CASE
+	WHEN IFNULL(i.inventory_id, 0) = 0 THEN "NOT available"
+    ELSE "Available"
+END AS "Availability Status"
+FROM film AS f
+LEFT JOIN inventory AS i
+ON f.film_id = i.film_id;
+