Find the names of all the customers.
select customer_name from customers
What are the names of customers who bought the product "Latte" before?
select t1.customer_name from customers as t1 join customer_orders as t2 on t1.customer_id = t2.customer_id join order_items as t3 on t2.order_id = t3.order_id join products as t4 on t3.product_id = t4.product_id where product_details = 'Latte'
Which customers never bought Latte"?
select customer_name from customers except select t1.customer_name from customers as t1 join customer_orders as t2 on t1.customer_id = t2.customer_id join order_items as t3 on t2.order_id = t3.order_id join products as t4 on t3.product_id = t4.product_id where product_details = 'Latte'