protected function patchDuplicateRow($d, $pKey, array $columns)
    {
        $id = $d[$pKey];
        if (isset($this->rData[$id])) {
            foreach ($columns as $c => $separator) {
                $this->rData[$id][$c] .= $separator.$d[$c];
            }
        } else {
            $this->rData[$id] = $d;
        }
    }