private void SetSaleText(string payment_method) //db에서 할인율 불러와서 계산해야함
{
StatisticsModel result = StatisticsVM.GetStatistics(payment_method);
WholeSalePrice = result.OriginalPrice;
PureSalePrice = result.PureSalePrice;
SalePrice = result.SalePrice;
DataContext = null;
DataContext = this;
}