private void DgvCompetition_SelectionChanged(object sender, EventArgs e) { int ri = dgvCompetition.CurrentRow.Index; lbMH.Text = dgvCompetition[1, ri].Value.ToString(); cNew = new COMPETION() { id = Convert.ToInt32(dgvCompetition[0, ri].Value), subtractID = dgvCompetition[1, ri].Value.ToString(), testDateBegin = Convert.ToDateTime(dgvCompetition[2, ri].Value), testTimeToLive = Convert.ToInt32(dgvCompetition[3, ri].Value), gradeid = Convert.ToInt32(dgvCompetition[4, ri].Value), idtest = Convert.ToInt32(dgvCompetition[5, ri].Value) }; var rs = TracNghiem.LayDanhSachKetQua(); var rt = rs.Where(s => s.idCom == Convert.ToInt32(dgvCompetition[0, ri].Value) && s.idStudent == temp.id).Select(s => s).SingleOrDefault(); if (rt != null) { lbScore.Text = string.Format("{0}", Math.Round((double)rt.score, 2)); } else { lbScore.Text = "Chưa có"; } }