CI_DB_active_record::group_by PHP Method

    function group_by($by)
    {
        if (is_string($by)) {
            $by = explode(',', $by);
        }
        foreach ($by as $val) {
            $val = trim($val);
            if ($val != '') {
                $this->ar_groupby[] = $this->_protect_identifiers($val);
                if ($this->ar_caching === TRUE) {
                    $this->ar_cache_groupby[] = $this->_protect_identifiers($val);
                    $this->ar_cache_exists[] = 'groupby';
                }
            }
        }
        return $this;
    }