Nested sets как удалить узел и все дочерние элементы?

DELETE FROM my_tree WHERE left_key >= $left_key AND right_ key <= $right_key;
UPDATE my_tree SET left_key = IF(left_key > $left_key, left_key – ($right_key - $left_key + 1), left_key), right_key = right_key – ($right_key - $left_key + 1) WHERE right_key > $right_key