public void LoginWithUser() { NguoiDungDAL loginWithUser = new NguoiDungDAL(); loginWithUser._nguoiDung = this._nguoiDung; KetQua = loginWithUser.LoginWithUser(); GridView grid = new GridView(); grid.DataSource = KetQua; grid.DataBind(); if (grid.Rows.Count != 0) { IsInvalid = true; _nguoiDung.HoTen = grid.Rows[0].Cells[0].Text; _nguoiDung.IdNguoiDung = int.Parse(grid.Rows[0].Cells[1].Text); } else { IsInvalid = false; } }