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

-- Exercise 1
SELECT DISTINCT category_name
FROM categories c JOIN products p
 ON c.category_id = p.category_id
WHERE (
SELECT DISTINCT category_name
FROM categories c JOIN products p
 ON c.category_id = p.category_id)
ORDER BY category_name
-- Exercise 2
SELECT product_name,list_price
FROM products
WHERE (
    SELECT product_name,list_price
	FROM products)
ORDER BY list_price DESC;
-- Exercise 3
SELECT category_name 
FROM categories
WHERE (
    SELECT product_id
		FROM products)
WHERE product_id NOT EXISTS
ORDER BY category_id DESC;
-- Exercise 4
SELECT email_address, order_id,sum(item_price) AS order_total
FROM administrators a JOIN orders o
  ON a.admin_id = o.admin_id
ORDER BY email_address ASC;

-- Exercise 4 part 2
__
-- Exercise 5
SELECT product_name, discount_percent
FROM products
ORDER BY discount_percent DESC;
-- Exercise 6
SELECT email_address, order_id, order_date
FROM administrators a JOIN orders o
on a.admin_id = o.order_id;