music_store_analysis_queries.sql

/* 1. Who is the senior most employee based on job title? */
SELECT * FROM employee
ORDER BY levels DESC LIMIT 1;

/* 2. Which countries have the most Invoices? */
SELECT billing_country, COUNT(*) as invoice_count FROM invoice
GROUP BY billing_country
ORDER BY invoice_count desc limit 1;

/* 3. What are top 3 values of total invoice? */
SELECT total from invoice
ORDER BY total DESC LIMIT 3;

/* 4. Which city has the best customers?Write a query 
that returns one city that has the highest sum of invoice totals.
Return both the city name & sum of all invoice totals */
SELECT billing_city, SUM(total) as invoice_total FROM invoice
GROUP BY billing_city 
ORDER BY invoice_total DESC LIMIT 1;

/* 5. Who is the best customer?Write a query that
 returns the person who has spent the most money */
 SELECT customer.customer_id,customer.first_name,customer.last_name,
 SUM(invoice.total) as total_sum FROM customer
 JOIN invoice ON customer.customer_id=invoice.customer_id
 GROUP BY customer.customer_id
 ORDER BY total_sum DESC LIMIT 1;
 
 /* 1.Write query to return the email, first name, last name, & Genre of all Rock
 Music listeners. Return your list ordered alphabetically by email starting with A */
 SELECT DISTINCT email,first_name,last_name FROM customer
 JOIN invoice ON invoice.customer_id=customer.customer_id
 JOIN invoice_line ON invoice_line.invoice_id=invoice.invoice_id
 WHERE track_id IN(
		SELECT track_id FROM track
        JOIN genre ON track.genre_id=genre.genre_id
        WHERE genre.name LIKE 'Rock'
			)
ORDER BY email;

/*2.Let's invite the artists who have written the most rock music in our dataset.
Write a query that returns the Artist name and total track count of the top 10 rock bands*/
SELECT artist.name, count(track.track_id) AS track_count FROM artist
JOIN album ON artist.artist_id=album.artist_id
JOIN track ON album.album_id=track.album_id
JOIN genre ON track.genre_id=genre.genre_id
WHERE genre.name LIKE 'Rock'
GROUP BY artist.artist_id
ORDER BY track_count DESC LIMIT 10;

/* 3.Return all the track names that have a song length longer than the average song length.
Return the Name and Milliseconds for each track. Order by the song length with the longest songs listed first*/
SELECT name, milliseconds FROM track
WHERE milliseconds> (SELECT AVG(milliseconds) FROM track)
ORDER BY milliseconds DESC;

/* 1.Find how much amount spent by each customer on artists? 
Write a query to return customer name, artist name and total spent*/ 
WITH best_selling_artist AS(
	SELECT artist.artist_id AS artist_id, artist.name AS artist_name, SUM(invoice_line.unit_price*invoice_line.quantity) AS total_sales
	FROM invoice_line
	JOIN track ON track.track_id = invoice_line.track_id
	JOIN album ON album.album_id = track.album_id
	JOIN artist ON artist.artist_id = album.artist_id
	GROUP BY 1
	ORDER BY 3 DESC
	LIMIT 1
)
SELECT c.customer_id, c.first_name, c.last_name, bsa.artist_name, SUM(il.unit_price*il.quantity) AS amount_spent
FROM invoice i
JOIN customer c ON c.customer_id = i.customer_id
JOIN invoice_line il ON il.invoice_id = i.invoice_id
JOIN track t ON t.track_id = il.track_id
JOIN album alb ON alb.album_id = t.album_id
JOIN best_selling_artist bsa ON bsa.artist_id = alb.artist_id
GROUP BY 1,2,3,4
ORDER BY 5 DESC;

/*2.We want to find out the most popular music Genre for each country.
We determine the most popular genre as the genre with the highest amount of purchases. 
Write a query that returns each country along with the top Genre. 
For countries where the maximum number of purchases is shared return all Genres*/
WITH popular_genre AS 
(
    SELECT COUNT(invoice_line.quantity) AS purchases, customer.country, genre.name, genre.genre_id, 
	ROW_NUMBER() OVER(PARTITION BY customer.country ORDER BY COUNT(invoice_line.quantity) DESC) AS RowNo 
    FROM invoice_line 
	JOIN invoice ON invoice.invoice_id = invoice_line.invoice_id
	JOIN customer ON customer.customer_id = invoice.customer_id
	JOIN track ON track.track_id = invoice_line.track_id
	JOIN genre ON genre.genre_id = track.genre_id
	GROUP BY 2,3,4
	ORDER BY 2 ASC, 1 DESC
)
SELECT * FROM popular_genre WHERE RowNo <= 1

/*3.Write a query that determines the customer that has spent the most on music for each country.
 Write a query that returns the country along with the top customer and how much they spent.
 For countries where the top amount spent is shared, provide all customers who spent this amount*/
 WITH Customter_with_country AS (
		SELECT customer.customer_id,first_name,last_name,billing_country,SUM(total) AS total_spending,
	    ROW_NUMBER() OVER(PARTITION BY billing_country ORDER BY SUM(total) DESC) AS RowNo 
		FROM invoice
		JOIN customer ON customer.customer_id = invoice.customer_id
		GROUP BY 1,2,3,4
		ORDER BY 4 ASC,5 DESC)
SELECT * FROM Customter_with_country WHERE RowNo <= 1