What is the company name of the customer who made the biggest amount of purchase in a single order before discount?
biggest amount of purchase in a single order refers to MAX(MULTIPLY(UnitPrice, Quantity)); before discount refers to Discount = 0
SELECT T1.CompanyName FROM Customers AS T1 INNER JOIN Orders AS T2 ON T1.CustomerID = T2.CustomerID INNER JOIN `Order Details` AS T3 ON T2.OrderID = T3.OrderID WHERE T3.Discount = 0 GROUP BY T1.CompanyName ORDER BY SUM(T3.UnitPrice * T3.Quantity) DESC LIMIT 1