public override CreditHistoryList GetCreditHistoryUsed(long userId)
        {
            CreditHistoryList ret = new CreditHistoryList();
            using (MySqlConnection conn = new MySqlConnection(GetConnectionString()))
            {
                using (MySqlCommand cmd = new MySqlCommand(QRY_GET_CREDITHISTORY_USED, conn))
                {
                    cmd.Parameters.Add("@userid", MySqlDbType.Int64).Value = userId;
                    try
                    {
                        conn.Open();
                        using (MySqlDataReader rdr = cmd.ExecuteReader())
                        {
                            while (rdr.Read())
                            {
                                long creditHistoryId = rdr.GetInt64(0);
                                long newUserId = rdr.GetInt64(1);
                                long productId = rdr.GetInt64(2);
                                int credits = rdr.GetInt32(3);
                                DateTime purchaseDate = rdr.GetDateTime(4);
                                int expired = rdr.GetInt32(5);
                                long transactionId = rdr.GetInt64(6);

                                ret.Add(new CreditHistory(creditHistoryId, newUserId, productId, credits, purchaseDate, expired, transactionId));
                            }
                        }
                    }
                    catch (Exception ex)
                    {
                        Logger.Instance.Write(LogLevel.Error, ex, "GetCreditHistoryUsed<Exception>");
                    }
                    finally
                    {
                        conn.Close();
                    }
                }
            }
            return ret;
        }
        public override List<CreditHistory> GetCreditHistory(long userId)
        {
            CreditHistoryList res = new CreditHistoryList();

            CreditHistoryList ret = new CreditHistoryList();
            CreditHistoryList added = GetCreditHistoryAdded(userId);
            CreditHistoryList used = GetCreditHistoryUsed(userId);

            // Now we have all the credits added and used for the specified user
            foreach (CreditHistory ch in added)
            {
                bool found = true;
                int credits = ch.Credits;
                while (found)
                {
                    if (used.Count > 0 && used[0].PurchaseDate < ch.PurchaseDate.AddYears(1))
                    {
                        credits -= used[0].Credits;
                        used.RemoveAt(0);
                    }
                    else
                    {
                        CreditHistory creditHistory = new CreditHistory(ch.CreditHistoryId,
                                                                        ch.UserId,
                                                                        ch.ProductId,
                                                                        credits,
                                                                        ch.PurchaseDate,
                                                                        ch.Expired,
                                                                        ch.TransactionId);
                        Transaction transaction = null;
                        using (MySqlConnection conn = new MySqlConnection(GetConnectionString()))
                        {
                            string QRY_GET_TRANSACTION_BY_USERID_AND_DATE = string.Empty;

                            if (creditHistory.TransactionId == 0)
                                QRY_GET_TRANSACTION_BY_USERID_AND_DATE = @"
                                                            SELECT * FROM `transaction`
                                                            WHERE `user_id`=@userid
                                                            AND `status`='OK'
                                                            AND (`date` BETWEEN SUBDATE(@transdate, interval 5 minute) AND ADDDATE(@transdate, interval 5 minute))
                                                            LIMIT 1
                                                        ";

                            else
                                QRY_GET_TRANSACTION_BY_USERID_AND_DATE = @"
                                                            SELECT * FROM `transaction`
                                                            WHERE `user_id`=@userid
                                                            AND `status`='OK'
                                                            AND `transaction_id`=@transactionId
                                                        ";

                            using (MySqlCommand cmd = new MySqlCommand(QRY_GET_TRANSACTION_BY_USERID_AND_DATE, conn))
                            {

                                cmd.Parameters.Add("@userid", MySqlDbType.Int64).Value = userId;
                                cmd.Parameters.Add("@transdate", MySqlDbType.DateTime).Value = creditHistory.PurchaseDate;
                                cmd.Parameters.Add("@transactionId", MySqlDbType.Int64).Value = creditHistory.TransactionId;

                                try
                                {
                                    conn.Open();
                                    using (MySqlDataReader rdr = cmd.ExecuteReader())
                                    {
                                        while (rdr.Read())
                                        {
                                            transaction = new Transaction();

                                            transaction.TransactionId = rdr.GetInt64(0);
                                            transaction.UserId = userId;
                                            transaction.Amount = rdr.GetDecimal(2);
                                            transaction.Date = rdr.GetDateTime(3);
                                            transaction.Description = rdr.GetString(4);
                                            transaction.ProductId = rdr.GetInt64(5);
                                            transaction.Status = rdr.GetString(6);
                                            transaction.StatusCode = rdr.GetString(7);
                                            transaction.Merchant = rdr.GetString(8);
                                            transaction.PaymentId = rdr.GetString(9);
                                            transaction.TransactionReference = rdr.GetString(10);
                                            transaction.PaymentMethod = rdr.GetString(11);

                                        }
                                    }
                                }
                                catch (Exception ex)
                                {
                                    Logger.Instance.Write(LogLevel.Error, ex, "GetCreditHistory<exception>");
                                }
                                finally
                                {
                                    conn.Close();
                                }
                            }
                        }
                        if (transaction != null)
                        {
                            creditHistory.Description = transaction.Description.Replace(".", ",") ?? "";
                            creditHistory.InvoiceFile = string.Format("INV{0}.pdf", transaction.PaymentId ?? "");
                        }
                        found = false;
                        ret.Add(creditHistory);
                    }
                }
            }

            List<CreditHistory> TempRes = (from obj in ret
                                           orderby obj.CreditHistoryId descending
                                           select obj).ToList<CreditHistory>();

            return TempRes;
        }