public void DataMaintenance(Employee anEmp, DB.DBOperation operation)
        {
            int index = 0;

            //perform a given database operation to the dataset in meory;
            employeeDB.DataSetChange(anEmp, operation);
            //perform operations on the collection
            switch (operation)
            {
            case DB.DBOperation.Add:
                //*** Add the employee to the Collection
                employees.Add(anEmp);
                break;

            case DB.DBOperation.Edit:
                index            = FindIndex(anEmp);
                employees[index] = anEmp;      // replace employee at this index with the updated employee
                break;

            case DB.DBOperation.Delete:
                index = FindIndex(anEmp);      // find the index of the specific employee in collection
                employees.RemoveAt(index);     // remove that employee form the collection
                break;
            }
        }