Users: email : text : primary key; first_name : text; last_name : text; street : text; house_number : int; postcode : text; city : text; country : text : nullable
Products: id : int : primary key, auto_increment; name : text; price : decimal(11,2); stock : int
Orders: id : int : primary key, auto_increment; user : text : foreign key references Users.email; status : int
OrderItem: order_id : int : foreign key references Orders.id; product_id : int : foreign key references Products.id; amount : int

Exercise	Title	Difficulty
Exercise 1	Find all users that ordered	3
Exercise 2	Find all users that never ordered	2
Exercise 3	Find all orders that were shipped to the same address	4
Exercise 4	Average price of products	3
Exercise 5	Searching in product names	1
Exercise 6	Second most expensive product	1
Exercise 7	Average order price per city	3
Exercise 8	Stock check	4
Exercise 11	Find the countries the users live in	2