What's more difficult is something like this:

UPDATE Products

SET UnitPrice = 0.9 * UnitPrice

WHERE ProductID IN

(

SELECT ProductID FROM(

SELECT ROW_NUMBER() OVER (ORDER BY UnitPrice DESC) AS Number, ProductID FROM Products) AS B

WHERE Number % 10 = 0

)

Or

UPDATE Products

SET UnitPrice = 0.9 * UnitPrice

WHERE ProductID IN

(

SELECT ProductID FROM(

SELECT ROW_NUMBER() OVER (ORDER BY UnitPrice DESC) AS Number, ProductID FROM Products) AS B

WHERE (Number >= 10 AND Number < 20)

OR (Number >= 50 AND Number < 60)

)