protected void btnThem_Click(object sender, EventArgs e)
 {
     try
     {
         string ma              = txtMa.Text;
         string congtac         = ma + "/" + txtCongTac.Text;
         CongTacTimeSheetDAO ct = new CongTacTimeSheetDAO();
         bool kq = ct.KiemTraMa(ma);
         if (kq == false)
         {
             bool them = ct.ThemMoi(ma, congtac, 0);
             if (them == true)
             {
                 lblThongBao.Text = "Thêm thành công!";
                 txtMa.Text       = "";
                 txtCongTac.Text  = "";
             }
             else
             {
                 lblThongBao.Text = "Fail!";
             }
         }
         else
         {
             lblThongBao.Text = "Mã đã tồn tại.";
         }
     }
     catch (Exception ex)
     { lblThongBao.Text = ex.Message; }
 }