Solved lab

sakila-joins.sql

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+USE sakila;
+
+-- 1
+SELECT
+    c.name AS category,
+    COUNT(fc.film_id) AS number_of_films
+FROM category AS c
+JOIN film_category AS fc
+    ON c.category_id = fc.category_id
+GROUP BY c.category_id, c.name
+ORDER BY number_of_films DESC, c.name ASC;
+
+-- 2
+SELECT
+    s.store_id,
+    ci.city,
+    co.country
+FROM store AS s
+JOIN address AS a
+    ON s.address_id = a.address_id
+JOIN city AS ci
+    ON a.city_id = ci.city_id
+JOIN country AS co
+    ON ci.country_id = co.country_id
+ORDER BY s.store_id;
+
+-- 3
+SELECT
+    st.store_id,
+    ROUND(SUM(p.amount), 2) AS total_revenue
+FROM store AS st
+JOIN staff AS sf
+    ON st.store_id = sf.store_id
+JOIN payment AS p
+    ON sf.staff_id = p.staff_id
+GROUP BY st.store_id
+ORDER BY st.store_id;
+
+-- 4
+SELECT
+    c.name AS category,
+    ROUND(AVG(f.length), 2) AS avg_running_time
+FROM category AS c
+JOIN film_category AS fc
+    ON c.category_id = fc.category_id
+JOIN film AS f
+    ON fc.film_id = f.film_id
+GROUP BY c.category_id, c.name
+ORDER BY avg_running_time DESC;
+
+-- 5
+SELECT
+    c.name AS category,
+    ROUND(AVG(f.length), 2) AS avg_running_time
+FROM category AS c
+JOIN film_category AS fc
+    ON c.category_id = fc.category_id
+JOIN film AS f
+    ON fc.film_id = f.film_id
+GROUP BY c.category_id, c.name
+HAVING AVG(f.length) = (
+    SELECT MAX(avg_length)
+    FROM (
+        SELECT AVG(f2.length) AS avg_length
+        FROM category AS c2
+        JOIN film_category AS fc2
+            ON c2.category_id = fc2.category_id
+        JOIN film AS f2
+            ON fc2.film_id = f2.film_id
+        GROUP BY c2.category_id, c2.name
+    AS category_avg
+    )
+);
+
+-- 6
+SELECT
+    f.title,
+    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 f.film_id, f.title
+ORDER BY times_rented DESC, f.title ASC
+LIMIT 10;
+
+-- 7
+SELECT
+    f.title,
+    i.store_id,
+    COUNT(i.inventory_id) AS copies_in_store,
+    CASE
+        WHEN COUNT(i.inventory_id) > 0 THEN 'Available'
+        ELSE 'NOT available'
+    END AS availability
+FROM film AS f
+LEFT JOIN inventory AS i
+    ON f.film_id = i.film_id
+    AND i.store_id = 1
+WHERE f.title = 'ACADEMY DINOSAUR'
+GROUP BY f.film_id, f.title, i.store_id;
+
+-- 8
+SELECT
+    f.title,
+    CASE
+        WHEN IFNULL(inv.copies, 0) > 0 THEN 'Available'
+        ELSE 'NOT available'
+    END AS availability
+FROM film AS f
+LEFT JOIN (
+    SELECT
+        film_id,
+        COUNT(*) AS copies
+    FROM inventory
+    GROUP BY film_id
+) AS inv
+    ON f.film_id = inv.film_id
+ORDER BY f.title ASC;