public function returning($col)
    {
        if (is_array($col)) {
            $this->clause_returning = array_merge($this->clause_returning, $col);
        } else {
            $this->clause_returning[] = $col;
        }
        return $this;
    }
public function returning($col)
    {
        if (is_array($col)) {
            $this->clause_returning = array_merge($this->clause_returning, $col);
        } else {
            $this->clause_returning[] = $col;
        }
        return $this;
    }
{@inheritDoc}