fillWorkerCombo

private void fillWorkerCombo()
        {

            numberCombo.Items.Clear();

            cnn = new SqlConnection(connectionString);


            using (cnn)
            {

                AutoCompleteStringCollection data = new AutoCompleteStringCollection();


                try
                {
                    cnn.Open();
                }
                catch (Exception ex)
                {
                    MessageBox.Show("Hiba az adatbázis megnyitása közben: " + ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Stop);
                    return;
                }

                SqlDataReader dr;

                try
                {



                    string sortQuery;
                    SqlCommand cmd;

                    if (sorting)
                    {
                        sortQuery = "SELECT Worker_Number, Error_Short, Machine, Create_Record, Modify_Record FROM Report_tbl WHERE Machine = @machine AND Error_Short = @errorshort AND Modify_Record BETWEEN @start_date AND @end_date";

                        cmd = new SqlCommand(sortQuery, cnn);

                        cmd.Parameters.AddWithValue("@machine", machineCombo.Text);
                        cmd.Parameters.AddWithValue("@errorshort", errorCombo.Text);
                        cmd.Parameters.AddWithValue("@start_date", monthCalendar1.SelectionRange.Start);
                        cmd.Parameters.AddWithValue("@end_date", monthCalendar1.SelectionRange.End.AddDays(1));

                    }
                    else
                    {
                        sortQuery = "SELECT Worker_Number, Error_Short, Machine, Create_Record, Modify_Record FROM Report_tbl WHERE Machine = @machine AND Error_Short = @errorshort";

                        cmd = new SqlCommand(sortQuery, cnn);

                        cmd.Parameters.AddWithValue("@machine", machineCombo.Text);
                        cmd.Parameters.AddWithValue("@errorshort", errorCombo.Text);




                    dr = cmd.ExecuteReader();

                    int workerNumber = 0;



                    while (dr.HasRows)
                    {
                        while (dr.Read())
                        {
                            int getIntFromDR = dr.GetInt32(0);

                            if (!numberCombo.Items.Contains(getIntFromDR))
                            {
                                workerNumber = getIntFromDR;
                                numberCombo.Text = workerNumber.ToString();
                                numberCombo.Items.Add(workerNumber.ToString());
                                numberCombo.AutoCompleteCustomSource = data;


                            }
                        }
                        dr.NextResult();
                    }
                    dr.Close();
                }
                catch (Exception ex)
                {
                    MessageBox.Show("521Hiba a lekérdezés közben: " + ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Stop);
                }
                cnn.Close();
            }

        }