<?php
    $userId = 1; // staring node
    $fetchedUsers = array(); // users, that are already fetched

    function doQuery($ids, $order = 1)
    {
        // searching by passed id/ids. If ids is array, using implode and sql-in.
        // getting result from sql, setting each element's key as user id
        // result will be like this:
        switch ($order) // is just imitation of recursive changing of resultset
        {
            case 1:
                return array(
                    2 => array(
                        'id' => 2, // may be omitted
                        'name' => 'Вася',
                        'parentId' => 0,
                    ),
                    5 => array(
                        'id' => 5,
                        'name' => 'Петя',
                        'parentId' => 0,
                    ),
                    7 => array(
                        'id' => 7,
                        'name' => 'Саша',
                        'parentId' => 0,
                    ),
                    18 => array(
                        'id' => 18,
                        'name' => 'Коля',
                        'parentId' => 0,
                    )
                );
            case 2:
                return array(
                    1 => array(
                        'id' => 1, // may be omitted
                        'name' => '1231',
                        'parentId' => 5,
                    ),
                    4 => array(
                        'id' => 4,
                        'name' => '21',
                        'parentId' => 5,
                    ),
                    12 => array(
                        'id' => 12,
                        'name' => '123123123',
                        'parentId' => 7,
                    ),
                    43 => array(
                        'id' => 43,
                        'name' => '112',
                        'parentId' => 18,
                    )
                );
            default:
                return array(
                    122 => array(
                        'id' => 122, // may be omitted
                        'name' => '122',
                        'parentId' => 12,
                    ),
                    123 => array(
                        'id' => 123,
                        'name' => '123',
                        'parentId' => 12,
                    ),
                    1122 => array(
                        'id' => 1122,
                        'name' => '1122',
                        'parentId' => 12,
                    ),
                    124 => array(
                        'id' => 124,
                        'name' => '124',
                        'parentId' => 12,
                    )
                );
        }
    }
    $order = 1; // needed for doQuery simulation.
    $users = doQuery($userId, $order); 
    do {
        $idsToFetch = array();
        if (is_array($users))
        {
            // finding all users, that are still not in result array ($fetchedUsers)
            $idsToFetch = array_diff_key($users, $fetchedUsers);
            if (empty($idsToFetch))
                break; // if array is empty, then no need to run query again. breaking the loop.
        
            $fetchedUsers += $users; // merging arrays by key
            $users = doQuery($idsToFetch, ++$order); // invoking next query
        }
    } while (!empty($idsToFetch)); // looping while have ids to fetch (anyhow loop stops iteration above - at the break operator)

    echo 'Queries done: ' . $order;
    echo '<pre>Fetched users';
    print_r($fetchedUsers);
    echo '</pre>';
    $tree = array();

    // the next step: to place all items on their places.
    // important to know the fact, that array elements are ordered in order, that were pushed in array
    // tree level was increasing, so one iteration gonna be enough.

    // that is really fast solution! and holds just a few lines
    foreach($fetchedUsers as $id => &$user) // passing value by reference is important
    {
        if ($user['parentId'] == 0) // no parent, then pushing to the root of the tree
            $tree[$id] =& $user; // however, do not forget to copy user by reference!
        else
            // that is all trickery. It comes up for any nesting level
            // but do not require recursion, or even second loop through users array
            // depends on that, we just copied variable above by reference!
            // so we are still changing source array, but tree is also being changed!
            $fetchedUsers[$user['parentId']]['items'][$id] =& $user;
    }
    // I seem, that is really fantastic solution. I was in luck anyway 

    unset($fetchedUsers);

    echo '<pre>Tree';
    print_r($tree);
    echo '</pre>';

<?php 
	mysql_connect('localhost','root1','root1');
	mysql_select_db('test2');


    $res = mysql_query("SELECT `id`,`name`,`parentId` FROM `table` WHERE `parentId`='1'");
	$count = mysql_num_rows($res);
	
	while($row = mysql_fetch_assoc($res))
	{
		$users[$row['id']] = $row;
	}
	$u = $users;
	while ($count > 0)
	{	
		$i++;
		$order = '';
		foreach ($u as $k => $v)
		{
			$order .= (empty($order))?NULL:",";
			$order .= $v['id'];
		}
		$u = NULL;
		$res = mysql_query("SELECT `id`,`name`,`parentId` FROM `table` WHERE `parentId` in (".$order.")");
		$count = mysql_num_rows($res);
		while($row = mysql_fetch_assoc($res))
		{
			$users[$row['id']] = $row;
			$u[$row['id']] = $row;
		}
	}
    // the next step: to place all items on their places.
    // important to know the fact, that array elements are ordered in order, that were pushed in array
    // tree level was increasing, so one iteration gonna be enough.

    // that is really fast solution! and holds just a few lines
    foreach($users as $id => &$user) // passing value by reference is important
    {
        if ($user['parentId'] == 1) // no parent, then pushing to the root of the tree
            $tree[$id] =& $user; // however, do not forget to copy user by reference!
        else
            // that is all trickery. It comes up for any nesting level
            // but do not require recursion, or even second loop through users array
            // depends on that, we just copied variable above by reference!
            // so we are still changing source array, but tree is also being changed!
            $users[$user['parentId']]['items'][$id] = &$user;
    }
    // I seem, that is really fantastic solution. I was in luck anyway 



    echo '<pre>Tree';
    print_r($tree);
    echo '</pre>';
?>