public void BindProductDetail(int productCode)
{
DALProduct obj = new DALProduct();
DataSet ds = obj.Product_GetDetail(productCode);
ddlCategory.SelectedValue = ds.Tables[0].Rows[0]["CategoryCode"].ToString();
txtProductName.Text = ds.Tables[0].Rows[0]["ProductName"].ToString();
txtPurchaseRate.Text = ds.Tables[0].Rows[0]["PurchaseRate"].ToString();
txtSaleRate.Text = ds.Tables[0].Rows[0]["SaleRate"].ToString();
txtExpiryDate.Text = Convert.ToDateTime(ds.Tables[0].Rows[0]["ExpiryDate"]).ToString("dd-MM-yyyy");
}