Solved lab

sql_joins_myfile.sql

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+-- 1. List the number of films per category.
+
+SELECT c.category_id as cat, COUNT(c.film_id) as number_of_films FROM sakila.film AS f
+JOIN sakila.film_category AS c
+ON c.film_id = f.film_id
+GROUP BY cat;
+
+
+-- 2. Retrieve the store ID, city, and country for each store.
+
+SELECT 
+s.store_id as store, 
+c.city_id as city, 
+co.country_id as country 
+FROM sakila.store AS s
+JOIN sakila.address as a
+ON s.address_id = a.address_id
+JOIN sakila.city AS c
+ON a.city_id = c.city_id
+JOIN sakila.country AS co
+ON c.country_id = co.country_id;
+
+
+
+-- 3. Calculate the total revenue generated by each store in dollars.
+
+SELECT store.store_id, SUM(payment.amount) AS total_revenue
+FROM store
+JOIN staff ON store.store_id = staff.store_id
+JOIN payment ON staff.staff_id = payment.staff_id
+GROUP BY store.store_id;
+
+
+
+-- 4. Determine the average running time of films for each category.
+
+
+SELECT category.name, ROUND(AVG(film.length), 2) AS average_running_time
+FROM category
+JOIN film_category ON category.category_id = film_category.category_id
+JOIN film ON film_category.film_id = film.film_id
+GROUP BY category.name;