FIGURE 1 Inefficient execution plan for version 1 of the stored procedure

    |--Filter(WHERE:(([Orders].[CustomerID]=[@CustomerID] OR 
[@CustomerID]=NULL) AND ([Orders].[EmployeeID]=[@EmployeeID] OR 
[@EmployeeID]=NULL)))
          |--Bookmark Lookup(BOOKMARK:([Bmk1000]), 
OBJECT:([tempdb].[dbo].[Orders]))
               |--Index Scan(OBJECT:([tempdb].[dbo].[Orders].[idx_unc_OrderID]),  
WHERE:(([Orders].[OrderID]=[@OrderID] OR [@OrderID]=NULL) AND 
([Orders].[OrderDate]=[@OrderDate] OR [@OrderDate]=NULL)))