How to recursively build a <select> with unknown tree depth

Question

I have a MySQL table with a tree data structure. The fields are _id, name and parentId. When the record hasn\'t a parent, parent

Answer 1

My final solution (thanks to Starx and varan):

function toSelect ($arr, $depth=0) {    
    $html = '';
    foreach ( $arr as $v ) {

        $html.= '';
        $html.= str_repeat('--', $depth);
        $html.= $v['name'] . '' . PHP_EOL;

        if ( array_key_exists('children', $v) ) {
            $html.= toSelect($v['children'], $depth+1);
        }
    }

    return $html;
}

echo '';
echo toSelect($array);
echo '';

Even the RecursiveIteratorIterator solution is good (thanks hakre).