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

function toSelect($arr, $depth = 0) {

    $html = '';

    foreach ( $arr as $v ) {           

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

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

    }


    return $html;
}