Array
(
    [0] => Array
        (
            [id] => 8
            [parent_id] => 6
        )

    [1] => Array
        (
            [id] => 2
            [parent_id] => 1
        )

    [2] => Array
        (
            [id] => 3
            [parent_id] => 1
        )

    [3] => Array
        (
            [id] => 4
            [parent_id] => 1
        )

    [4] => Array
        (
            [id] => 5
            [parent_id] => 2
        )

    [5] => Array
        (
            [id] => 1
            [parent_id] => 0
        )

    [6] => Array
        (
            [id] => 6
            [parent_id] => 2
        )

    [7] => Array
        (
            [id] => 7
            [parent_id] => 3
        )

)

----

0=>Array
(
    [id] => 8
    [parent_id] => 6
)

----

1=>Array
(
    [id] => 2
    [parent_id] => 1
)

----

2=>Array
(
    [id] => 3
    [parent_id] => 1
)

----

3=>Array
(
    [id] => 4
    [parent_id] => 1
)

----

4=>Array
(
    [id] => 5
    [parent_id] => 2
)

----

5=>Array
(
    [id] => 1
    [parent_id] => 0
)

----

6=>Array
(
    [id] => 6
    [parent_id] => 2
)

----

7=>Array
(
    [id] => 7
    [parent_id] => 3
)
1
1.2
1.2.5
1.2.6
1.2.6.8
1.3
1.3.7
1.4