private void btnAccept_Click(object sender, EventArgs e)
        {
            bool success = Products_SuppliersDB.UpdateProductsSuppliers(oldSuppProd, newSuppProd);

            if (success)
            {
                this.DialogResult = DialogResult.OK;
                ManagementForm frm = new ManagementForm();
                frm.Refresh();
            }
            else
            {
                this.DialogResult = DialogResult.Retry;
            }
        }