老师我的代码都是按照你视频中的内容写得。但执行的时候出现错误，不解：--Warning: mysql_fetch_assoc() expects parameter 1 to be resource, boolean given in D:\xampp\htdocs\test\listcate.php on line 9 Array ( )------- 

---代码如下----请老师帮我看看哪里出现错误？

<?php

include('db.inc.php');

function getList($pid = 0,&$result=array(),$spac = 0)

{

$spac+=2;

$sql = "SELECT * FROM tb_cate WHERE pid = $pid";

$res = mysql_query($sql);

while($row = mysql_fetch_assoc($res))

{

$row['catename'] = str_repeat('&nbsp;',$spac).'|__'.$row['catename'];

$result[]=$row;

getList($row['id'],$result,$spac);

}

return $result;

}

$rs = getList();

print_r($rs);

?>