public long InsertQuery(string sql, SQLiteTransaction transaction)
        {

            SQLiteCommand sqlCommand;
            if (transaction != null)
            {
                sqlCommand = new SQLiteCommand(sql, this.connection, transaction);
            }
            else
            {
                sqlCommand = new SQLiteCommand(sql, this.connection);
            }

            try
            {
                int n_rows = sqlCommand.ExecuteNonQuery();
            }
            catch (Exception ex)
            {
                Logger.WriteLine("Exception: {0}", ex);
            }
            finally
            {
                sqlCommand.Dispose();
            }
            return this.connection.LastInsertRowId;
        }