FIGURE 2 Inefficient execution plan for version 2 of the stored procedure

     |--Clustered Index Scan(OBJECT:([tempdb].[dbo].[Orders].[idx_cl_OrderDate]), 
WHERE:((([Orders].[OrderID]=If ([@OrderID]<>NULL) then [@OrderID] else 
[Orders].[OrderID] AND [Orders].[CustomerID]=If ([@CustomerID]<>NULL) 
then [@CustomerID] else [Orders