protected function _buildColsQuery($aIdentCols, $blIdentCols = true)
    {
        $sQ = '';
        foreach ($aIdentCols as $iCnt => $aCol) {
            if ($sQ) {
                $sQ .= ', ';
            }

            $sViewTable = $this->_getViewName($aCol[1]);
            if (!$blIdentCols && $this->_isExtendedColumn($aCol[0])) {
                $sQ .= $this->_getExtendedColQuery($sViewTable, $aCol[0], $iCnt);
            } else {
                $sQ .= $sViewTable . '.' . $aCol[0] . ' as _' . $iCnt;
            }
        }

        return $sQ;
    }