การเพิ่มข้อมูลแบบมีเงือนไข c# ในกรณีที่เลือกแล้วทำการเพิ่มตามที่เลือกช่วยนะนำหน่อยครับ

private void butSave_Click(object sender, EventArgs e)
        {

            MySqlConnection connection = new MySqlConnection(MyConnectionString);
            MySqlCommand cmd;
            connection.Open();
            cmd = connection.CreateCommand();

            string[] Start;
            Start = new string[12];
            Start[0] = txtStr1.Text.ToString();
            Start[1] = txtStr2.Text.ToString();
            Start[2] = txtStr3.Text.ToString();
            Start[3] = txtStr4.Text.ToString();
            Start[4] = txtStr5.Text.ToString();
            Start[5] = txtStr6.Text.ToString();
            Start[6] = txtStr7.Text.ToString();
            Start[7] = txtStr8.Text.ToString();
            Start[8] = txtStr9.Text.ToString();
            Start[9] = txtStr10.Text.ToString();
            Start[10] = txtStr11.Text.ToString();
            Start[11] = txtStr12.Text.ToString();


            string[] Finish;
            Finish = new string[12];
            //string[] Finish = new string[12];
            Finish[0] = txtEnd1.Text.ToString();
            Finish[1] = txtEnd2.Text.ToString();
            Finish[2] = txtEnd3.Text.ToString();
            Finish[3] = txtEnd4.Text.ToString();
            Finish[4] = txtEnd5.Text.ToString();
            Finish[5] = txtEnd6.Text.ToString();
            Finish[6] = txtEnd7.Text.ToString();
            Finish[7] = txtEnd8.Text.ToString();
            Finish[8] = txtEnd9.Text.ToString();
            Finish[9] = txtEnd10.Text.ToString();
            Finish[10] = txtEnd11.Text.ToString();
            Finish[11] = txtEnd12.Text.ToString();
            string[] period_id;
            period_id = new string[12];
            //string[] Finish = new string[12];
            period_id[0] = "";
            period_id[1] = "";
            period_id[2] = "";
            period_id[3] = "";
            period_id[4] = "";
            period_id[5] = "";
            period_id[6] = "";
            period_id[7] = "";
            period_id[8] = "";
            period_id[9] = "";
            period_id[10] = "";
            period_id[11] = "";

            for (int k = 0; k < 12; k++)
            {
                
                cmd = connection.CreateCommand();
                cmd.CommandText = "INSERT INTO tb_period VALUES('',@Start,@Finish)";
              //  cmd.CommandText = "INSERT INTO tb_period VALUES(@period_id,@Start,@Finish)";

                //cmd.Parameters.AddWithValue("@period_id", period_id[k]);
                cmd.Parameters.AddWithValue("@Start", Start[k]);
                cmd.Parameters.AddWithValue("@Finish", Finish[k]);
                cmd.ExecuteNonQuery();
               
            }

            MessageBox.Show("คุณได้เพิ่มข้อมูลเรียบร้อยแล้ว");
            connection.Close();

        }


    }