What is the total amount of sales made in the year 1997?
year 1997 refers to year(OrderDate) = 1997; total amount of sales refers to (UnitPrice * Quantity)
SELECT SUM(T2.UnitPrice * T2.Quantity * (1 - T2.Discount)) FROM Orders AS T1 INNER JOIN `Order Details` AS T2 ON T1.OrderID = T2.OrderID WHERE T1.OrderDate LIKE '1997%'