[SOLVED] List all Sub/Sub-Sub etc.. Categories (Category Tree)

[Hyaku_]

Hi!
I'm trying to list category tree, but I'm having problems listing sub-sub.. categories. This is my Category field:
[code]+-------+----------+------+-----+---------+----------------+
| Field | Type    | Null | Key | Default | Extra          |
+-------+----------+------+-----+---------+----------------+
| ID    | int(11)  | NO  | PRI | NULL    | auto_increment |
| NAME  | longtext | YES  |    | NULL    |                |
| P_ID  | int(11)  | YES  |    | NULL    |                |
+-------+----------+------+-----+---------+----------------+
[/code]
This is my code So far:
[quote]function list_cat(){

$query = "SELECT * FROM CATEGORY WHERE P_ID = 0";
$query_exec = mysql_query($query);

while($data = mysql_fetch_array($query_exec)){
echo $data['NAME'] . "<BR>";

$s_query = "SELECT * FROM CATEGORY WHERE P_ID = " . $data['ID'];
$s_query_exec = mysql_query($s_query);

while($s_data = mysql_fetch_array($s_query_exec)){
echo "<font size='1'>" . $s_data['NAME'] . "</font><br>";
}


}

}[/quote]
For example I have these values into the database:
[code]+----+-----------------+------+
| ID | NAME            | P_ID |
+----+-----------------+------+
|  1 | Animals        |    0 |
|  2 | Dogs            |    1 |
|  3 | Cats            |    1 |
|  4 | Black          |    2 |
|  5 | White          |    2 |
+----+-----------------+------+
[/code]
P_ID is Categories Parrent ID. Now my function prints this:

Animals
[i]Dogs[/i]
[i]Cats[/i]

Dogs and Cats are sub-categories of Animals, but Dogs sub-categorie contains sub-sub categorie White and Black. I want to be able to print thous under Dog sub-categorie. And I want to sub-sub-sub.. categorie count to be unlimited, so I need my function to be able to always print the full categorie tree. In this case like this:

Animals
[i]Dogs[/i]
[sub][i]White
Black[/i][/sub]
[i]Cats[/i]

Any tips please?! I guess I could use arrays, but I don't have a really good plan how! Thanks!

[trq]

Id'e suggest taking a look at [url=http://www.phpriot.com/d/articles/php/application-design/nested-trees-1/index.html]Nested Sets[/url].

[Barand]

You need a recursive function

[code]
<?php
include '../test/db.php';

function list_cat($parent, $level=0)  {
    $sql = "SELECT id, name FROM categories
            WHERE p_id = '$parent'
            ORDER BY name";
    $res = mysql_query($sql) or die(mysql_error());
    while (list($id, $name) = mysql_fetch_row($res)) {
        $indent = str_repeat('&nbsp;', $level*3);
        echo "$indent$name<br>";
        list_cat($id, $level+1);
    }
}

/**
* call the function
*/
list_cat(0);
?>
[/code]

[Hyaku_]

Thanks alot, man!!

[palace]

What does the code look like that updates the database with the category information?

I'm getting my head around how the principle works but can't picture how the admin form would be like to put values into the table.