private void LayMaKhachHangDoLenTextBox() { AutoCompleteStringCollection auto = new AutoCompleteStringCollection(); DataTable dt = KhachHang_BLL.LayMaKhachHang(); foreach (DataRow item in dt.Rows) { auto.Add(item[0].ToString()); auto.Add(item[1].ToString()); } txtTuKhoa.AutoCompleteMode = AutoCompleteMode.SuggestAppend; txtTuKhoa.AutoCompleteSource = AutoCompleteSource.CustomSource; txtTuKhoa.AutoCompleteCustomSource = auto; }