public function autoIncrement()
    {
        $col = &$this->col_defs[count($this->col_defs) - 1];
        $col['autoincrement'] = true;
        return $this;
    }
public function autoIncrement()
    {
        $col = &$this->col_defs[count($this->col_defs) - 1];
        $col['autoincrement'] = true;
        return $this;
    }
{@inheritDoc}