I assume you are looking for something beyond just retrieving the last
five orders - say using the data in the Orders table to control the
data being retrieved from some other table entirely.

This gets the date range for the most recent five orders by customer.

SELECT CustomerID,
      MIN(OrderDate) as StartDate,
      MAX(OrderDate) as EndDate
 FROM Orders as A
WHERE OrderID IN
      (SELECT TOP 5 B.OrderID
         FROM Orders as B
        WHERE A.CustomerID = B.CustomerID
        ORDER BY B.OrderDate DESC)
GROUP BY CustomerID

I will leave it to you to apply that data to whatever table is
required.

Roy Harvey
Beacon Falls, CT

Lee,

If (your version of) SQL Server implements them, you may want to look
at the windowing functions, and specifically the framing clause.
Here's an example of a simple moving average:

SELECT
  keyword,
  avg(qty) over (order by orderdate range between 5 preceding and
current row) as n
from
  orders

The important part is the "range between 5 preceding and current row"

--Jeff