src/Phossa/Query/Clause/GroupByTrait.php
protected function buildGroupBy()/*# : array */
    {
        $result = [];
        foreach ($this->clause_groupby as $grp) {
            $result[] = $grp[0] ? $grp[1] : $this->quote($grp[1]);
        }
        return $result;
    }
protected function buildGroupBy()/*# : array */
    {
        $result = [];
        foreach ($this->clause_groupby as $grp) {
            $result[] = $grp[0] ? $grp[1] : $this->quote($grp[1]);
        }
        return $result;
    }
Build GROUP BY

@return array
@access protected