public void loadData() { cboMaSV.Items.Add("Choose Student"); cboMaSV.SelectedIndex = cboMaSV.FindStringExact("Choose Student"); btnSearch.Enabled = false; ds = SinhVienDAO.LoadSinhVienToComboBox(); DataTable dt = ds.Tables[0]; for (int i = 0; i < dt.Rows.Count; i++) { cboMaSV.Items.Add(dt.Rows[i].Field <int>("MASV")); } }