private void btCheckin_Click(object sender, EventArgs e)
        {
            if (txtMaCN_tkCC.Text == "")
            {
                MessageBox.Show("Không có dữ liệu để checkin", "Thông báo");
                return;
            }
            string   day    = DateTime.Now.DayOfWeek.ToString();
            TimeSpan giotoi = DateTime.Now.TimeOfDay;

            if (giotoi.Hours <= 11)
            {
                bool ditre = false;
                if (giotoi.Hours > 7)
                {
                    ditre = true;
                }
                GioLamViec glv = new GioLamViec("CALV1", day, giotoi, new TimeSpan(0, 0, 0), ditre, new TimeSpan(0), DateTime.Now, txtMaCN_tkCC.Text, txtMaCN_tkCC.Text);
                try
                {
                    cnb.AddGioLamViec(glv);
                }
                catch (Exception p)
                {
                    MessageBox.Show(p.ToString());
                }
            }
            if (giotoi.Hours >= 11 && giotoi.Hours <= 18)
            {
                bool ditre = false;
                if (giotoi.Hours > 11)
                {
                    ditre = true;
                }
                GioLamViec glv = new GioLamViec("CALV2", day, giotoi, new TimeSpan(0, 0, 0), ditre, new TimeSpan(0), DateTime.Now, txtMaCN_tkCC.Text, txtMaCN_tkCC.Text);
                try
                {
                    cnb.AddGioLamViec(glv);
                }
                catch (Exception p)
                {
                    MessageBox.Show(p.ToString());
                }
            }
            if (giotoi.Hours > 18)
            {
                bool ditre = false;
                if (giotoi.Hours > 18)
                {
                    ditre = true;
                }
                GioLamViec glv = new GioLamViec("CALV3", day, giotoi, new TimeSpan(0, 0, 0), ditre, new TimeSpan(0), DateTime.Now, txtMaCN_tkCC.Text, txtMaCN_tkCC.Text);
                try
                {
                    cnb.AddGioLamViec(glv);
                }
                catch (Exception p)
                {
                    MessageBox.Show(p.ToString());
                }
            }
            try
            {
                dgvCheck.DataSource = cnb.ViewGioLamViec("SELECT MaCaLV,Thu,GioToi,GioVe,DiTre,Tong,[Ngay/Thang/Nam],GioLamViec.MaNV,MaGioLamViec,Ho,Ten,Hinh FROM GioLamViec,CongNhan WHERE GioLamViec.MaNV=CongNhan.MaNV AND Thu='" + day + "'").ToList();
                cnb.AddLich(txtMaCN_CC.Text, DateTime.Now);
            }
            catch (Exception p)
            {
                MessageBox.Show(p.ToString());
            }
        }