请教下php的Resource问题？

<?phpheader("Content-type: text/html; charset=utf-8");   if(!empty($_POST['username'])){  $name=$_POST['username'];}  if(!empty($_POST['pwd'])){  $pwd=$_POST['pwd'];}    function sqlDql($name,$pwd){  $conn=mysql_connect("localhost","root","root");  if(!$conn){  die("连接失败".mysql_error());  }  mysql_select_db("test",$conn) or die(mysql_error());  //设置字符集    mysql_query("set names utf8");  $sql="select * from zhuche;";    $res=mysql_query($sql,$conn) or die(mysql_error());    while($row=mysql_fetch_row($res)){          if($name==$row[1]){       	echo "用户名已经存在<br/>";       	echo "<a href='login.php'>返回注册页面</a>";        // die(mysql_free_result($res)."连接".mysql_close($conn));        mysql_free_result($res);          mysql_close($conn);        exit();    	          }       }    $sql2="insert into zhuche (Username,password) values ('".$name."','".$pwd."');";    $res2=mysql_query($sql2,$conn) or die(mysql_error());    echo "<table border='1px solid black'>";    echo "<tr><td>序号</td><td>用户</td><td>密码</td></tr>";    while($row=mysql_fetch_row($res)){     	echo "<tr>";     	foreach($row as $key=> $val){     	 echo "<td>--".$val."</td>";     	 }     	echo "</tr>";     	}    echo "</table>";	     mysql_free_result($res);      mysql_close($conn);  }  sqlDql($name,$pwd);?>