Csharp MySql数据库数据解析问题

enter image description here}

private void btn_process_Click(object sender, EventArgs e)
{
connection_class.open_connection();
MySqlCommand cmd = new MySqlCommand("INSERT INTO `invoice`( `registerNumber`,`vehicleModel`,`fuelType`,`km`,`mechanicName`,`date`,`job1`,`job2`,`job3`,`job4`,`job5`,`job6`,`job7`,`job8`,`discount`,`price`)  VALUES (@registerNumber,@vehicleModel,@fuelType,@km,@mechanicName,@date,@job1,@job2,@job3,@job4,@job5,@job6,@job7,@job8,@discount,@price)", connection_class.con);
            cmd.Parameters.Clear();
            cmd.Parameters.AddWithValue("@registerNumber", txt_vehicleNumber);
            cmd.Parameters.AddWithValue("@vehicleModel", txt_vehicleModle);
            cmd.Parameters.AddWithValue("@fuelType", drp_fuelType);
            cmd.Parameters.AddWithValue("@km", txt_km);
            cmd.Parameters.AddWithValue("@mechanicName", drp_mechanic);
            cmd.Parameters.AddWithValue("@date", lbl_date);
            cmd.Parameters.AddWithValue("@job1", lbl_job1);
            cmd.Parameters.AddWithValue("@job2", lbl_job2);
            cmd.Parameters.AddWithValue("@job3", lbl_job3);
            cmd.Parameters.AddWithValue("@job4", lbl_job4);
            cmd.Parameters.AddWithValue("@job5", lbl_job5);
            cmd.Parameters.AddWithValue("@job6", lbl_job6);
            cmd.Parameters.AddWithValue("@job7", lbl_job7);
            cmd.Parameters.AddWithValue("@job8", lbl_job8);
            cmd.Parameters.AddWithValue("@discount", lbl_totDiscount);
            cmd.Parameters.AddWithValue("@price", lbl_total);

            cmd.ExecuteNonQuery();
            connection_class.close_connection();
            MessageBox.Show("Invoice printed !!!");
}

我想将这些数据正确地发送到表中. 例如:代替"Guna.UI2.WinForms.Internal.PlaceholderTextBox，文本:343447.00"这是我想发送的"343447"