在一个使用mysql的windows窗体.net应用程序中，我的产品具有多个制造操作。每个操作都有一个预期的开始日期和预期的完成日期。我想做的是，当用户更改第一次操作的日期时，更改该产品后续操作的开始日期和结束日期（推送日期）。到目前为止，我已经设法更改了以下操作的日期，但它们都是相同的。如果你能帮我写些代码，那就太好了。我应该改用datatable吗？以下是我目前的情况：

# region Push the predicted start date in planning table for same product id if end date is pushed forward

        DateTime oldStartDate = DateTime.Now;
        DateTime oldFinishDate = DateTime.Now;
        DateTime dt3 = DateTime.Parse(predicted_delivery.Text);
        DateTime dt4 = DateTime.Parse(new_predicted_delivery.Text);
        if(dt3.Date == dt4.Date)
        {
            return;
        }
        else
        {
            int delay = (dt4 - dt3).Days;

            ConnectionStringSettings conSettings1 = ConfigurationManager.ConnectionStrings["shopmanagerConnectionString1"];
            MySqlConnection con1 = new MySqlConnection(conSettings1.ToString());
            MySqlCommand cmd1 = new MySqlCommand(@"select * from shopmanager.planning where part_id = @part_id;", con1);
            MySqlDataReader myReader1;

            try
            {
                con1.Open();
                cmd1.Parameters.AddWithValue("@part_id", temp_part.item_id);
                myReader1 = cmd1.ExecuteReader();

                while (myReader1.Read())
                {
                    oldStartDate = myReader1.GetDateTime("predicted_start_date");
                    oldFinishDate = myReader1.GetDateTime("predicted_delivery");
                }
                cmd1.Parameters.Clear();

            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
            con1.Close();
            newStartDate = oldStartDate.AddDays(delay);
            newFinishDate = oldFinishDate.AddDays(delay);

            UpdateNewStartDate();
        }
        #endregion

    }
    #endregion

    #region Update new start and finish dates
    private void UpdateNewStartDate()
    {
        ConnectionStringSettings conSettings = ConfigurationManager.ConnectionStrings["shopmanagerConnectionString1"];
        MySqlConnection con = new MySqlConnection(conSettings.ToString());
        MySqlCommand cmd = new MySqlCommand(@"update shopmanager.planning set predicted_start_date = @predicted_start_date, predicted_delivery = @predicted_delivery where part_id = @part_id", con);

        try
        {
            con.Open();
            cmd.Parameters.AddWithValue("@predicted_start_date", newStartDate);
            cmd.Parameters.AddWithValue("@predicted_delivery", newFinishDate);
            cmd.Parameters.AddWithValue("@part_id", temp_part.item_id);

            cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
        con.Close();