From 443f4a39075cfc6a5cfe0796ea319e387146a2f7 Mon Sep 17 00:00:00 2001
From: Alex <amateu1991@hotmail.es>
Date: Sun, 29 Mar 2026 15:22:32 +0200
Subject: [PATCH] Solved lab

---
 lab-sql-joins.sql | 90 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 lab-sql-joins.sql

diff --git a/lab-sql-joins.sql b/lab-sql-joins.sql
new file mode 100644
index 0000000..98ab8ed
--- /dev/null
+++ b/lab-sql-joins.sql
@@ -0,0 +1,90 @@
+-- 1. List the number of films per category.
+SELECT c.name,
+       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
+ORDER BY number_of_films DESC;
+-- 2. Retrieve the store ID, city, and country for each store.
+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. Calculate the total revenue generated by each store in dollars.
+SELECT st.store_id,
+       SUM(p.amount) AS total_revenue
+FROM payment p
+JOIN staff s 
+    ON p.staff_id = s.staff_id
+JOIN store st 
+    ON s.store_id = st.store_id
+GROUP BY st.store_id
+ORDER BY total_revenue DESC;
+-- 4. Determine the average running time of films for each category.
+SELECT c.name AS category,
+       ROUND(AVG(f.length),2) AS avg_duration
+FROM film f
+JOIN film_category fc 
+    ON f.film_id = fc.film_id
+JOIN category c 
+    ON fc.category_id = c.category_id
+GROUP BY c.name
+ORDER BY avg_duration DESC;
+-- 5. Identify the film categories with the longest average running time.
+SELECT c.name AS category,
+       AVG(f.length) AS avg_duration
+FROM film f
+JOIN film_category fc 
+    ON f.film_id = fc.film_id
+JOIN category c 
+    ON fc.category_id = c.category_id
+GROUP BY c.name
+ORDER BY avg_duration DESC
+LIMIT 5;
+-- 6. Display the top 10 most frequently rented movies in descending order.
+SELECT f.title,
+       COUNT(r.rental_id) AS rental_count
+FROM rental r
+JOIN inventory i 
+    ON r.inventory_id = i.inventory_id
+JOIN film f 
+    ON i.film_id = f.film_id
+GROUP BY f.title
+ORDER BY rental_count DESC
+LIMIT 10;
+-- 7. Determine if "Academy Dinosaur" can be rented from Store 1.
+SELECT f.title,
+       COUNT(i.inventory_id) AS available_copies
+FROM film f
+JOIN inventory i 
+    ON f.film_id = i.film_id
+LEFT JOIN rental r 
+    ON i.inventory_id = r.inventory_id
+    AND r.return_date IS NULL
+WHERE f.title = "Academy Dinosaur"
+  AND i.store_id = 1
+  AND r.rental_id IS NULL
+GROUP BY f.title;
+-- 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 f.title,
+       CASE 
+           WHEN IFNULL(COUNT(i.inventory_id), 0) = 0 THEN 'NOT available'
+           WHEN COUNT(r.rental_id) < COUNT(i.inventory_id) THEN 'Available'
+           ELSE 'NOT available'
+       END AS availability
+FROM film f
+LEFT JOIN inventory i 
+    ON f.film_id = i.film_id
+LEFT JOIN rental r 
+    ON i.inventory_id = r.inventory_id
+    AND r.return_date IS NULL
+GROUP BY f.film_id, f.title;
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