Database: retail_world
Question: List the top five most costly products in 1998.
SQL: SELECT T3.ProductName FROM Orders AS T1 INNER JOIN `Order Details` AS T2 ON T1.OrderID = T2.OrderID INNER JOIN Products AS T3 ON T2.ProductID = T3.ProductID WHERE T1.OrderDate LIKE '1998%' ORDER BY T3.UnitPrice + T1.Freight DESC LIMIT 5