Loop through unlimited nested categories

[oohoohoohooh]

Hi, I have a table setup called categories with the following structure:

- cat_id (primary key)
- subcat_id
- cat_name

If a category is within another category it's subcat_id would be the cat_id of the category it is within. This allows me to have unlimited subcats within subcats. Hope all is clear so far. I setup the following function to store the contents of the table in an array (so I don't have lots of queries):

function get_categories() {
	$cats	= array();

	$query = $GLOBALS['db']->query("SELECT * FROM " . $GLOBALS['config']['db']['prefix'] . "cats ORDER BY cat_id");

	while ($cat = $GLOBALS['db']->fetch_array($query)) {
		$cats[$cat['subcat_id']][] = $cat;
	}

	return $cats;
}

Now I need some way of looping through the array to display the contents. This is where I get stuck as I'm not too great with arrays. Below is the kind of output I wish to display based on the array at the bottom:

Books, Music, DVD
   - Books
   - DVD
   - Music
      - Pop
      - Rock
   - Video
Electronics & Office
   - Electronics
   - Mobile Phones
   - Camera & Photo

I put print_r(get_categories()) so you could see the contents of the array we're dealing with and I got:

Array
(
    [0] => Array
        (
            [0] => Array
                (
                    [cat_id] => 1
                    [subcat_id] => 0
                    [cat_name] => Books, Music, DVD
                )

            [1] => Array
                (
                    [cat_id] => 2
                    [subcat_id] => 0
                    [cat_name] => Electronics & Office
                )

        )

    [1] => Array
        (
            [0] => Array
                (
                    [cat_id] => 5
                    [subcat_id] => 1
                    [cat_name] => Books
                )

            [1] => Array
                (
                    [cat_id] => 6
                    [subcat_id] => 1
                    [cat_name] => DVD
                )

            [2] => Array
                (
                    [cat_id] => 7
                    [subcat_id] => 1
                    [cat_name] => Music
                )

            [3] => Array
                (
                    [cat_id] => 8
                    [subcat_id] => 1
                    [cat_name] => Video
                )

        )

    [2] => Array
        (
            [0] => Array
                (
                    [cat_id] => 9
                    [subcat_id] => 2
                    [cat_name] => Electronics
                )

            [1] => Array
                (
                    [cat_id] => 10
                    [subcat_id] => 2
                    [cat_name] => Mobile Phones
                )

            [2] => Array
                (
                    [cat_id] => 11
                    [subcat_id] => 2
                    [cat_name] => Camera & Photo
                )

        )

    [7] => Array
        (
            [0] => Array
                (
                    [cat_id] => 26
                    [subcat_id] => 7
                    [cat_name] => Pop
                )

            [1] => Array
                (
                    [cat_id] => 27
                    [subcat_id] => 7
                    [cat_name] => Rock
                )

        )

)

I'd appreciate it if you could help. Thanks

 

[sleipnir214]

To paraphrase the movie "The Graduate":

I want to say one word to you. Just one word. Recursion.


If there is no explicit limit to the depth of nesting, then you are going to have to write a recursive function to list all members.


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