多级遍历

<?php


header('content-type:text/html;charset=utf-8');
$conn=mysql_connect('localhost','root','')or die('数据库连接失败!');
mysql_select_db('test',$conn);
mysql_query('set names utf8');
$sql="select * from base_area where pid=0";
$result=mysql_query($sql);
$data=array();
$prov=array();
$city=array();
$xianxian=array();


while($pro=mysql_fetch_assoc($result)){


$sql_city="select * from base_area where pid={$pro['areaid']}";
$citys=mysql_query($sql_city);
while($ci=mysql_fetch_assoc($citys)){
$sql_xian="select * from base_area where pid={$ci['areaid']}";
$xians=mysql_query($sql_xian);
while($xi=mysql_fetch_assoc($xians)){
$xianxian["{$xi['areaid']}"]=$xi['areaid'];
}

$city["{$ci['areaid']}"]=$xianxian;
}


$prov["{$pro['areaid']}"]=$city;
$data['prov']=$prov;
}




var_dump($data);