bazar.Accrual.ShowOldDebts C# (CSharp) Method

        private void ShowOldDebts()
        {
            string sql = "SELECT accrual.month, accrual.year, SUM(money) as debt FROM (" +
                "SELECT accrual_id, SUM(count * price) as money FROM accrual_pays WHERE accrual_id IN " +
                "(SELECT id FROM accrual WHERE contract_id = @contract)" +
                "GROUP BY accrual_id " +
                "UNION ALL SELECT accrual_id, -SUM(sum) as money FROM credit_slips WHERE accrual_id IN " +
                "(SELECT id FROM accrual WHERE contract_id = @contract) " +
                "GROUP BY accrual_id ) as sumtable " +
                "LEFT JOIN accrual ON accrual.id = sumtable.accrual_id " +
                "GROUP BY accrual_id";
            decimal TotalDebt = 0;
            int count = 0;
            string DebtsText = "";
            int year = Convert.ToInt32 (comboAccuralYear.ActiveText);
            try
            {
                TreeIter iter;
                MySqlCommand cmd = new MySqlCommand(sql, QSMain.connectionDB);
                comboContract.GetActiveIter ( out iter);
                cmd.Parameters.AddWithValue("@contract", comboContract.Model.GetValue (iter, 1));
                MySqlDataReader rdr = cmd.ExecuteReader ();

                while(rdr.Read ())
                {
                    if(rdr.GetDecimal ("debt") <= 0)
                        continue;
                    if( rdr.GetInt32 ("year") > year  || ( rdr.GetInt32 ("year") == year && rdr.GetInt32 ("month") >= comboAccrualMonth.Active))
                        continue;
                    if(DebtsText != "")
                        DebtsText += "\n";
                    DateTime Month = new DateTime(rdr.GetInt32 ("year"), rdr.GetInt32("month"), 1);
                    if(rdr.GetInt32 ("year") == year)
                    {
                        DebtsText += String.Format ("{0:MMMM} = <span foreground=\"red\">{1:C}</span>", Month, rdr.GetDecimal ("debt"));
                    }
                    else
                    {
                        DebtsText += String.Format ("{0:Y} = <span foreground=\"red\">{1:C}</span>", Month, rdr.GetDecimal ("debt"));
                    }
                    TotalDebt += rdr.GetDecimal ("debt");
                    count ++;
                }
                rdr.Close ();
                if (count == 0)
                    return;
                if (count > 5)
                {
                    labelDebts.LabelProp = String.Format ("за {0} месяцев - {1:C}", count, TotalDebt);
                }
                else
                {
                    labelDebts.LabelProp = DebtsText;
                }
            }
            catch (Exception ex)
            {
                logger.Warn(ex, "Ошибка вычисления прошлого долга!");
            }
        }