请教一个序列化和反序列化的问题

<?php
include "includes/inc-setup.php";
class npc
{
var $name;
var $die;
var $time;
function creatnpc($npc,$n,$d,$t)
{
$this->name=$n;
$this->die=$d;
$this->time=$t;
}
}
$npc1=new npc();
$npc2=new npc();
$npc3=new npc();
$npc1->creatnpc('$npc1','野兔','0','300');
$npc2->creatnpc('$npc2','野狗','0','300');
$npc3->creatnpc('$npc3','野兔','0','300');
echo "<br>";
echo "npc1=";
print_r($npc1);
$npcs=serialize(array($npc1,$npc2,$npc3));
echo "<br>";
echo "插入的序列化serialize=";
print_r($npcs);
$query = ("INSERT INTO cc_wupin (`userid`,`wupin`) VALUES ('1','$npcs')");
echo "<br>";
if($db->query( $query )){echo "serialize插入成功";}
else{echo "serialize插入失败或原来就有";}
echo "<br>";
$N=$db->fetch($db->query("SELECT * FROM cc_wupin WHERE userid=1"));
if($N){echo "serialize读取成功";}
else{echo "serialize读取失败";}
$npcs1=$N[wupin];
$npcs2=unserialize($npcs1);
echo "<br>";
echo "数据表取出：";
print_r($N);
echo "<br>";
echo "<br>";
echo "读取的反序列unserialize=";
print_r($npcs2);
#echo $npcs2[0]->$name;
echo "<br>";
?>