ต้องการ select ข้อมูลมากกว่า 1 ตาราง OOP ผู้รู้ตอบทีครับ

<?php
define("DB_HOST","localhost");
define("DB_USER","root");
define("DB_PASS","root");
define("DB_NAME","test");
?>

<?php
class Class_DB 
{
	private $charset = "UTF8";
	private $rs;
	private $_fetch_array = array();

	public function __construct($host,$user,$pass,$db_name)
	{
		mysql_connect($host,$user,$pass) or die(mysql_error());
		mysql_query("SET NAMES ".$this->charset);
		mysql_query("USE $db_name");
	}
	public function query($strsql) //รับคำสั่ง sql เข้ามา query
	{
		$this->rs= mysql_query($strsql);
	}
	public function num_rows()	//เช็คจำนวนแถว
	{
		return mysql_num_rows($this->rs);
	}
	//---mysql fetch array()--//
	public function fetch_array()
	{
		if(count($this->_fetch_array)>0)
		{
			return $this->_fetch_array;
		}
		else
		{
			while($row=mysql_fetch_array($this->rs))
			{
				$this->_fetch_array[] = $row;
			}
			return $this->_fetch_array;
		}
	}
	//---End mysql fetch array() ---//

	public function fetch_row()
	{
		return mysql_fetch_row($this->rs);
	}
}
?>

<?php
session_start(); //เพื่อใช้งาน session
include_once("lib/config.inc.php");
include_once("lib/class_db.inc.php");

$db = new Class_DB(DB_HOST,DB_USER,DB_PASS,DB_NAME);
$db->query("select banner_url from advertise");

echo "จำนวนแถวมของ tb_user คือ: ".$db->num_rows();

while(list($user_id)=$db->fetch_row()) {
	echo "<p>ข้อมูล: ".$user_id. "</p>";
}
?>