// Them
        public void Them()
        {
            fmPopupNCC fm = new fmPopupNCC("Thêm nhà cung cấp");

            fm.StartPosition = FormStartPosition.CenterParent;
            if (fm.ShowDialog() == DialogResult.OK)
            {
                while (!ctrlData.Them <NhaCungCap>(new NhaCungCap(fm.txtMa.Text, fm.txtTen.Text, fm.txtSDT.Text, fm.txtDiaChi.Text)))
                {
                    MessageBox.Show("Mã cung cấp đã bị trùng!");
                    if (fm.ShowDialog() != DialogResult.OK)
                    {
                        return;
                    }
                }
            }
        }
        // Sua
        public void Sua(string Ma)
        {
            var nsx = ctrlData.ListItems <NhaCungCap>(Ma, "Ma", Const.TextFindOption.Absolute)[0];
            //
            fmPopupNCC fm = new fmPopupNCC("Sửa nhà cung cấp");

            fm.StartPosition  = FormStartPosition.CenterParent;
            fm.txtMa.ReadOnly = true;
            fm.txtMa.Text     = nsx.Ma;
            fm.txtTen.Text    = nsx.Ten;
            fm.txtSDT.Text    = nsx.SDT;
            fm.txtDiaChi.Text = nsx.DiaChi;
            //
            if (fm.ShowDialog() == DialogResult.OK)
            {
                if (!ctrlData.Sua <NhaCungCap>(new NhaCungCap(Ma, fm.txtTen.Text, fm.txtSDT.Text, fm.txtDiaChi.Text)))
                {
                    MessageBox.Show("Sửa thất bại!");
                    return;
                }
            }
        }