private void btSave_Click(object sender, EventArgs e)
        {
            int      r       = dtGridView.CurrentCell.RowIndex;
            string   tempDID = dtGridView.Rows[r].Cells[0].Value.ToString();
            district ProvQ   = db.districts.Single(x => x.province_id == tempDID);

            ProvQ.district_id   = txtPID.Text;
            ProvQ.district_name = txtPName.Text;
            db.SubmitChanges();
        }
        private void btSave_Click(object sender, EventArgs e)
        {
            int     r       = dtGridView.CurrentCell.RowIndex;
            string  tempCID = dtGridView.Rows[r].Cells[0].Value.ToString();
            commune ComQ    = db.communes.Single(x => x.commune_id == tempCID);

            ComQ.district_id  = txtDID.Text;
            ComQ.commune_id   = txtCID.Text;
            ComQ.commune_name = txtCName.Text;
            ComQ.degree       = Convert.ToInt32(txtDegree.Text);
            db.SubmitChanges();
        }