private void btn_Purchase_History_Click(object sender, RoutedEventArgs e)
{
cc.OpenConnection();
if (cc.BillPreview1("select COUNT(*) from Stock", billExistValue) > 0)
{
cc.CloseConnection();
PurchaseHistory ph = new PurchaseHistory();
this.NavigationService.Navigate(ph);
}
else
{
MessageBox.Show("No Bills to Show");
}
}
