数据库数据变成树型结构

<?php
$arrData= array(
	array(
		"id" => "1",
		"pid" => "0",
		"name" => "山东"
	),
	array(
		"id" => "2",
		"pid" => "0",
		"name" => "云南"
	),
	array(
		"id" => "3",
		"pid" => "1",
		"name" => "济南"
	),
	array(
		"id" => "4",
		"pid" => "2",
		"name" => "大理"
	),
	array(
		"id" => "7",
		"pid" => "3",
		"name" => "历下区"
	),
	array(
		"id" => "8",
		"pid" => "7",
		"name" => "大明湖"
	),
	array(
		"id" => "9",
		"pid" => "1",
		"name" => "青岛"
	),
	array(
		"id" => "10",
		"pid" => "3",
		"name" => "**县"
	),
);

$arrReData = array();
$result = array();
foreach($arrData as &$data){
	$arrReData[$data["id"]] = $data;
	if($data["pid"]!="0" && isset($arrReData[$data["pid"]])){
		if(!isset($arrReData[$data["pid"]]["children"])){
			$arrReData[$data["pid"]]["children"] = array();
		}
		$arrReData[$data["pid"]]["children"][] = &$arrReData[$data["id"]];
	}else{
		$result[] = &$arrReData[$data["id"]];
	}
}

print_r($result);

Array
(
    [0] => Array
        (
            [id] => 1
            [pid] => 0
            [name] => 山东
            [children] => Array
                (
                    [0] => Array
                        (
                            [id] => 3
                            [pid] => 1
                            [name] => 济南
                            [children] => Array
                                (
                                    [0] => Array
                                        (
                                            [id] => 7
                                            [pid] => 3
                                            [name] => 历下区
                                            [children] => Array
                                                (
                                                    [0] => Array
                                                        (
                                                            [id] => 8
                                                            [pid] => 7
                                                            [name] => 大明湖
                                                        )

                                                )

                                        )

                                    [1] => Array
                                        (
                                            [id] => 10
                                            [pid] => 3
                                            [name] => **县
                                        )

                                )

                        )

                    [1] => Array
                        (
                            [id] => 9
                            [pid] => 1
                            [name] => 青岛
                        )

                )

        )

    [1] => Array
        (
            [id] => 2
            [pid] => 0
            [name] => 云南
            [children] => Array
                (
                    [0] => Array
                        (
                            [id] => 4
                            [pid] => 2
                            [name] => 大理
                        )

                )

        )

)