private void btnSelectSale_Click(object sender, EventArgs e)
        {
            var clientCred = new ClientCredentialsForm();

            if (gridSales.SelectedRows.Count != 0)
            {
                var row = gridSales.SelectedRows[0];

                if (gridSales["Id", row.Index] != null)
                {
                    var result = clientCred.ShowDialog();

                    if (result == DialogResult.OK)
                        SelectSale(Int32.Parse(gridSales["Id", row.Index].Value.ToString()), txtCardBarcode.Text, clientCred.Phone);
                }
            }
        }
        private void gridSales_CellDoubleClick(object sender, DataGridViewCellEventArgs e)
        {
            var selectedId = gridSales["Id", e.RowIndex].Value.ToString();

            var clientCred = new ClientCredentialsForm();

            var result = clientCred.ShowDialog();

            if (result == System.Windows.Forms.DialogResult.OK)
                SelectSale(Int32.Parse(selectedId), txtCardBarcode.Text, clientCred.Phone);
        }