Listing 2: Script That Creates Version 1 of the Stored Procedure
CREATE PROC dbo.usp_GetOrders
  @OrderID    AS INT      = NULL,
  @CustomerID AS NCHAR(5) = NULL,
  @EmployeeID AS INT      = NULL,
  @OrderDate  AS DATETIME = NULL
AS

SELECT OrderID, CustomerID, EmployeeID, OrderDate, filler
FROM dbo.Orders
WHERE (OrderID    = @OrderID    OR @OrderID    IS NULL)
  AND (CustomerID = @CustomerID OR @CustomerID IS NULL)
  AND (EmployeeID = @EmployeeID OR @EmployeeID IS NULL)
  AND (OrderDate  = @OrderDate  OR @OrderDate  IS NULL);
GO