algorithm help

[uidzer0b]

Hey everyone,

I'm a long time lurker, first time poster 🙂 I'm having a little trouble writing an algorithm to create a hierarchal structure from a database which looks like this:

      parent_id | child_id    |
----------------+-------------+
              1 |           2 |
              2 |           3 |
              3 |           4 |
              3 |           5 |
              5 |           6 |
              5 |           7 |

So coming out of the database, I get an array which looks like this:

Array
(
    [0] => Array
        (
            [parent_id] => 1
            [child_id] => 2
        )

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

[2] => Array
    (
        [parent_id] => 3
        [child_id] => 4
    )
...

I would like to put this into an array which represents the following structure:

1
 \
  2
   \
    3
   / \
  4   5
     / \
   6    7 

Can anyone point me in the right direction?

Thanks!

Ben

[halojoy]

You already have a structure there, defined.
Question is what you want to implement this to?
A folder structure?
A data structure?
Something else?

[uidzer0b]

I need the structure to fully represent the hierarchy of the categories, much like a folder structure. ie:

Array
(
    [1] => Array
        (
            [children] => Array
                              (
                               [2] => Array
                                        (
                                            [children] => Array
                                                              (
                                                               [3] => ...

[Horizon88]

This has been worked over a few dozen times here in the past, and a very good article from sitepoint is listed. If you search for "recursive category display" and other variants of the same on the board's search page, you'll find a lot of results. I actually had the same problem and it's listed in the search results as resolved. 😉