public virtual ObjectResult<Sales_by_Year_Result> Sales_by_Year(Nullable<System.DateTime> beginning_Date, Nullable<System.DateTime> ending_Date)
{
var beginning_DateParameter = beginning_Date.HasValue ?
new ObjectParameter("Beginning_Date", beginning_Date) :
new ObjectParameter("Beginning_Date", typeof(System.DateTime));
var ending_DateParameter = ending_Date.HasValue ?
new ObjectParameter("Ending_Date", ending_Date) :
new ObjectParameter("Ending_Date", typeof(System.DateTime));
return ((IObjectContextAdapter)this).ObjectContext.ExecuteFunction<Sales_by_Year_Result>("Sales_by_Year", beginning_DateParameter, ending_DateParameter);
}