private void Button_Click_8(object sender, RoutedEventArgs e)
        {
            int n = 0;

            n = inputFreight();
            if (n == 1)
            {
                TBHelf.Clear();
                TBFormula.Clear();
            }
        }
        /// <summary>
        /// 公式保存按钮
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Button_Click_10(object sender, RoutedEventArgs e)
        {
            var    a          = this.DG2.SelectedItem;
            var    b          = a as DataRowView;
            string freight_id = "";

            try
            {
                freight_id = b.Row[0].ToString();
                updateFreight(freight_id);
                TBHelf.Clear();
                TBFormula.Clear();
            }
            catch (Exception e1)
            {
                MessageBox.Show("删除失败" + e1.Message);
            }
        }
 private void Button_Click_2(object sender, RoutedEventArgs e)
 {
     TBHelf.Text += "<W≤";
     TBHelf.Focus();
     TBHelf.SelectionStart = TBHelf.Text.Length;
 }