public IEnumerable<TL_MENU_ByIdResult> TL_MENU_ById(int? menuID)
 {
     try
     {
         using (var db = new OOAD_EDUManagementDataContext())
         {
             return db.TL_MENU_ById(menuID).ToList();
         }
     }
     catch (Exception e)
     {
         return null;
     }
 }