Database: customers_and_orders
Question: Count the number of different customers who have bought a Monitor Product.
SQL:
SELECT count(DISTINCT T3.customer_id) FROM Order_items AS T1 JOIN Products AS T2 ON T1.product_id  =  T2.product_id JOIN Customer_orders AS T3 ON T3.order_id  =  T1.order_id WHERE T2.product_name  =  "Monitor"