/** * @param Select $select * @return string */ public function _renderSelectGroupBy(Select $select) { $str = ""; if (count($select->getGroup())) { $groupCols = $select->getGroup(); array_walk($groupCols, function (&$col) { $col = $this->_renderColumn($col); }); $str = "GROUP BY"; $str .= " "; $separator = ", "; $str .= implode($separator, $groupCols); } return $str; }