Zeiterfassung.AddWorkerToProject.AddWorkers_Click C# (CSharp) Метод

        private void AddWorkers_Click(object sender, EventArgs e)
        {
            try
            {
                foreach (object itemChecked in arbeiterListe.CheckedItems)
                {
                    if (SqlConnection.CountStatement("SELECT COUNT(miID) FROM tmita_proj WHERE miID = " +
                        ((ListItem)itemChecked).DatabankID +
                        " AND mpAktiv = 0") > 0)
                    {
                        SqlConnection.ExecuteStatement("UPDATE tmita_proj SET mpAktiv = 1 WHERE miID = " +
                            ((ListItem)itemChecked).DatabankID + " AND prID = " + prID);
                    }
                    else
                    {
                        SqlConnection.ExecuteStatement("INSERT INTO tmita_proj(miID, prID, mpAktiv) " +
                            "VALUES (" + ((ListItem)itemChecked).DatabankID + ", " + prID + ",1)");
                    }
                }
                this.DialogResult = DialogResult.OK;
                this.Close();
            }
            catch (MySqlException ex)
            {
                MessageBox.Show("Es kam zu einem Problem mit der Datenbank." + Environment.NewLine +
                "Fehlernummer: " + ex.Number + Environment.NewLine +
                "Fehlerbeschreibung: " + ex.Message, "Fehler", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }