protected function _buildSelectStart()
        {
            $fragment = 'SELECT ';
            $result_columns = join(', ', $this->_resultColumns);

            if (!is_null($this->_limit) &&
                self::$_config[$this->_connection_name]['limit_clause_style'] === One::LIMIT_STYLE_TOP_N) {
                $fragment .= "TOP {$this->_limit} ";
            }

            if ($this->_distinct) {
                $result_columns = 'DISTINCT ' . $result_columns;
            }

            $fragment .= "{$result_columns} FROM " . $this->_quoteIdentifier($this->_table_name);

            if (!is_null($this->_table_alias)) {
                $fragment .= " " . $this->_quoteIdentifier($this->_table_alias);
            }

            return $fragment;
        }