private void bindingNavigatorSaveItem_Click(object sender, EventArgs e)
 {
     if (ds.HasChanges())
     {
         tableUpdate = new Renting_Management_System.BLL.TableUpdate();
         tableUpdate.Update(ds);
     }
 }
 public void Save(DataSet dataSet)
 {
     tableUpdate = new Renting_Management_System.BLL.TableUpdate();
     tableUpdate.Update(dataSet);
 }