Solved subqueries lab

solutions.sql

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+USE sakila;
+
+-- 1. Determine the number of copies of the film "Hunchback Impossible" 
+-- that exist in the inventory system.
+SELECT
+	f.title,
+    COUNT(i.inventory_id) AS number_of_copies
+FROM film f
+JOIN inventory i
+	ON f.film_id = i.film_id
+WHERE f.title = 'Hunchback Impossible'
+GROUP BY f.title;
+
+-- 2. List all films whose length is longer than the average length of 
+-- all the films in the Sakila database.
+SELECT
+	f.title,
+    f.length
+FROM film f
+WHERE f.length > (
+SELECT AVG(f.length)
+FROM film f
+);
+
+-- 3. Use a subquery to display all actors who appear 
+-- in the film "Alone Trip".
+SELECT
+	a.first_name,
+    a.last_name
+FROM actor a
+WHERE actor_id IN(
+	SELECT fa.actor_id
+    FROM film_actor fa
+    WHERE film_id IN(
+		SELECT f.film_id
+        FROM film f
+        WHERE f.title = 'Alone Trip'
+    )
+);
+
+-- BONUS 4. Sales have been lagging among young families,
+-- and you want to target family movies for a promotion. 
+-- Identify all movies categorized as family films.
+SELECT
+	f.title
+FROM film f
+WHERE film_id IN (
+	SELECT fc.film_id
+    FROM film_category fc
+    WHERE category_id = (
+		SELECT c.category_id
+		FROM category c
+		WHERE c.name = 'Family')
+);
+
+-- BONUS 5. Retrieve the name and email of customers from Canada
+-- using both subqueries and joins.
+-- To use joins, you will need to identify the relevant tables
+-- and their primary and foreign keys.
+
+-- SUBQUERIES
+SELECT
+	cu.first_name,
+    cu.last_name,
+    cu.email
+FROM customer cu
+WHERE address_id IN(
+	SELECT a.address_id
+    FROM address a
+    WHERE city_id IN(
+		SELECT ci.city_id
+        FROM city ci
+        WHERE country_id IN(
+			SELECT co.country_id
+            FROM country co
+            WHERE co.country = 'Canada'
+        )
+    )
+)
+;
+
+-- JOINS
+SELECT
+	cu.first_name,
+    cu.last_name,
+    cu.email
+FROM customer cu
+JOIN address a
+	ON	cu.address_id = a.address_id
+JOIN city ci
+	ON a.city_id = ci.city_id
+JOIN country c
+	ON ci.country_id = c.country_id
+WHERE c.country = 'Canada';
+
+-- BONUS 6. Determine which films were starred by the most prolific actor
+-- in the Sakila database. A prolific actor is defined as the actor who
+-- has acted in the most number of films.
+-- First, you will need to find the most prolific actor and then
+-- use that actor_id to find the different films that he or she starred in.
+SELECT
+	f.title
+FROM film f
+WHERE film_id IN(
+	SELECT fa.film_id
+    FROM film_actor fa
+    WHERE actor_id = (
+		SELECT fa.actor_id
+        FROM film_actor fa
+        GROUP BY fa.actor_id
+        ORDER BY COUNT(film_id) DESC
+        LIMIT 1
+    )
+);    
+
+-- BONUS 7. Find the films rented by the most profitable customer
+-- in the Sakila database. You can use the customer and payment
+-- tables to find the most profitable customer, i.e., 
+-- the customer who has made the largest sum of payments.
+SELECT DISTINCT
+	f.title
+FROM film f
+JOIN inventory i
+	ON f.film_id = i.film_id
+JOIN rental r
+	ON i.inventory_id = r.inventory_id
+WHERE r.customer_id =(
+	SELECT customer_id
+	FROM payment
+    GROUP BY customer_id
+    ORDER BY SUM(amount) DESC
+    LIMIT 1
+);
+
+-- BONUS 8. Retrieve the client_id and the total_amount_spent
+-- of those clients who spent more than the average of the 
+-- total_amount spent by each client.
+-- You can use subqueries to accomplish this.
+SELECT 
+	customer_id AS client_id,
+    SUM(amount) AS total_amount_spent
+FROM payment 
+GROUP BY customer_id
+HAVING SUM(amount) > (
+	SELECT AVG(total_spent)
+    FROM (
+		SELECT
+			customer_id,
+            SUM(amount) AS total_spent
+        FROM payment
+        GROUP BY customer_id
+    ) AS customer_totals
+);
+