public int GetID(int ID)
        {

            int ID = Convert.ToInt32(uow.repo.GetQueryable().Where(rh => rh.ID== ID && rh.Status == 0).OrderByDescending(o => o.Rev).Select(s=>s.ID));
            return ID;
        }

int ID = Convert.ToInt32(
          uow.repo.GetQueryable()
                  .Where(rh => rh.ID== ID && rh.Status == 0)
                  .OrderByDescending(o => o.Rev)
                  .Select(s=>s.ID) //this still is a collection
                  .FirstOrDefault()); //this takes the first one.