Problem_05.sql

-- Problem_05.sql
--
-- Suppose that a website contains two tables, the Customers table and the Orders table. Write a SQL query to find all customers who never order anything.
-- 
-- Table: Customers.
-- +----+-------+
-- | Id | Name  |
-- +----+-------+
-- | 1  | Joe   |
-- | 2  | Henry |
-- | 3  | Sam   |
-- | 4  | Max   |
-- +----+-------+
-- 
-- Table: Orders.
-- +----+------------+
-- | Id | CustomerId |
-- +----+------------+
-- | 1  | 3          |
-- | 2  | 1          |
-- +----+------------+
--
--Using the above tables as example, return the following:
--
-- +-----------+
-- | Customers |
-- +-----------+
-- | Henry     |
-- | Max       |
-- +-----------+

SELECT Name AS Customers 
	FROM Customers 
WHERE Id NOT IN 
	(SELECT CustomerId FROM Orders);