N level Category Tree using php and mysql

PHP
6

Thanks for the replies guys.
I have tried to get that done using this code.

I am using this class


$sql = mysql_query("select * from testcategories where parent_id=0 order by id asc ");
while($rs = mysql_fetch_array($sql))
{
	echo "<B>-".$name = $rs['catname']."</b><br>";
	$id = $rs['id'];
	$data.= $this->GetSubCat($id);
	echo $data;
}

var $dash = 0;
function GetSubCat($pid)
{
	$this->dash++;
	$subsql = "select * from testcategories where parent_id=".$pid;
	$rs = mysql_query($subsql);
	for($i=0;$i<=$this->dash;$i++)
	{
		$DashDisp  .= "-";
	}
	while($res = mysql_fetch_array($rs))
	{
		echo "<br>".$DashDisp.$name= $res['catname']."<br>";
		$id = $res['id'];
		$dataSub .= $this->GetSubCat($id);
	}
	$this->dash = 0;
	return $dataSub;
}

But still it is not showing properly like a tree.