my-guitar-shop-database-exersices/How-to-code-summary-queries.sql

-- Exercise 1

SELECT COUNT(order_id),
	SUM(tax_amount)
FROM orders;

-- Exercise 2

SELECT category_name,
	COUNT(product_id) AS count,
    MAX(list_price) AS max_price
FROM categories c JOIN products p
ON c.category_id = p.category_id
GROUP BY category_name
ORDER BY category_name DESC;

-- Exercise 3

SELECT c.email_address,
	SUM(item_price) * quantity,
    SUM(discount_amount) * quantity
FROM orders o JOIN order_items i 
		ON o.order_id = i.order_id
    JOIN customers c 
    ON o.customer_id = c.customer_id
GROUP BY c.customer_id
ORDER BY item_price DESC;

-- Exercise 4

SELECT c.email_address,
	COUNT(i.order_id),
    SUM(item_price - discount_amount) * quantity AS 'total_amount'
FROM orders o JOIN order_items i
		ON i.order_id = o.order_id
	JOIN customers c
		ON o.customer_id = c.customer_id
GROUP BY email_address
HAVING COUNT(i.order_id) > 1
ORDER BY SUM(item_price - discount_amount) * COUNT(i.order_id) DESC;

-- Exercise 5

SELECT c.email_address,
	COUNT(i.order_id),
    SUM(item_price - discount_amount) * quantity AS 'total_amount'
FROM orders o JOIN order_items i
		ON i.order_id = o.order_id
	JOIN customers c
		ON o.customer_id = c.customer_id
WHERE i.item_price > 400
GROUP BY email_address
HAVING COUNT(i.order_id) > 1
ORDER BY SUM(item_price - discount_amount) * COUNT(i.order_id) DESC;

-- Exercise 6

SELECT product_name,
    SUM(item_price - discount_amount) * quantity AS 'total_amount'
FROM products p JOIN order_items i
	ON p.product_id = i.product_id
GROUP BY product_name WITH ROLLUP;

-- Exercise 7

SELECT email_address,
    COUNT(product_id) AS 'distinct_products'
FROM customers c JOIN orders o
	ON c.customer_id = o.customer_id
JOIN order_items i 
	ON o.order_id = i.order_id
GROUP BY email_address
HAVING COUNT(o.order_id) > 1;