protected function getPosition($id)
    {
        $cols = [
            self::COLUMN_LEFT,
            self::COLUMN_RIGHT,
            'width' => new Expression(self::COLUMN_RIGHT . ' - ' . self::COLUMN_LEFT . ' + 1'),
        ];

        $select = $this->getSelect();

        $where = new Where;
        $where->equalTo($this->getPrimaryKey(), $id);
        $select->columns($cols)->where($where);

        $row = $this->fetchResult($select)->current();

        return $row;
    }