Problem with recursive function

[Busch]

I can't get my recursive function to append a variable ($sub_cats) each time a query is run.

CODE:

$this_cat_id = $arg['category'];

function get_all_sub_cats ($this_cat_id, $sub_cats='') {

    $sub_cats_result = mysql_query("SELECT category_id, category_parent FROM default_categories WHERE category_parent = '" . $this_cat_id . "'"); 
    //echo $sub_cats_result;
    if (@mysql_num_rows($sub_cats_result) >= 1) {
        while ($sub_cat = mysql_fetch_array($sub_cats_result)) {
            $this_cat_id = $sub_cat['category_id'];
            $sub_cats .= $sub_cat['category_id'] . "','";
            get_all_sub_cats ($this_cat_id, $sub_cats);
        }
    }            
    return $sub_cats;
}


$all_sub_cats = get_all_sub_cats ($this_cat_id, $sub_cats); 

I want to keep appending $sub_cats with the sub category ID's. But for a category that has 4 sub-categories it's only returning 1 sub-category deep.

What am I doing wrong?

[etheon]

Actually, you're not using the returned value of your recursive function.

The code should be :

$this_cat_id = $arg['category'];

function get_all_sub_cats ($this_cat_id, $sub_cats='') {

    $sub_cats_result = mysql_query("SELECT category_id, category_parent FROM default_categories WHERE category_parent = '" . $this_cat_id . "'"); 
    //echo $sub_cats_result;
    if (@mysql_num_rows($sub_cats_result) >= 1) {
        while ($sub_cat = mysql_fetch_array($sub_cats_result)) {
            $this_cat_id = $sub_cat['category_id'];
            $sub_cats .= $sub_cat['category_id'] . "','";
            $sub_cats .= get_all_sub_cats ($this_cat_id, $sub_cats);
        }
    }            
    return $sub_cats;
}


$all_sub_cats = get_all_sub_cats ($this_cat_id, $sub_cats); 

[Busch]

that was it! thanks and welcome to SP.

eric

[logic_earth]

Functions are so much easier to understand and go though when you keep them simple. Also you should do some checking on the var that is being submitted.

function get_all_sub_cats ($id, $sub = '') {

    // Sanity Check
    if (!is_scalar($id)) { return -1; }
    $id = mysql_real_escape_string(stripslashes((string)$id));

    $results = mysql_query("SELECT category_id FROM default_categories WHERE category_parent = '" . $id . "'");

    if (mysql_num_rows($results) > 0) {

        while ($row = mysql_fetch_assoc($results)) {

            $sub .= $sub_cat['category_id'] . "','";
            $sub .= get_all_sub_cats($row['category_id'], $sub);

        }

    }

    return $sub;

}