From 2071650d0d4c6be8fe709334d24f5663128e0390 Mon Sep 17 00:00:00 2001
From: letter-b <letterb.ff@gmail.com>
Date: Wed, 18 Mar 2026 21:10:37 +0000
Subject: [PATCH] Lab done

---
 joins_lab.sql | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 joins_lab.sql

diff --git a/joins_lab.sql b/joins_lab.sql
new file mode 100644
index 0000000..73482d1
--- /dev/null
+++ b/joins_lab.sql
@@ -0,0 +1,81 @@
+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;
\ No newline at end of file