一个PHP比较简单的有关问题

<br /><? <br />	// class_user.php <br />class UserInfo{ <br />   private $userName;  //属性,用户名 <br />   private $passWord;  //属性, <br />   private $userGrade; //属性,用户级别<br />   private $row; <br />   private $userInfo; //存储数据库返回信息的数组变量. <br />	  <br />	    public function __construct($sql){ <br />	        require_once("db_config.php"); //包含配置信息. <br />	        $result= mysql_query($sql, $conn); // 执行查询语句 <br />	        $this->userInfo = mysql_fetch_array($result); //返回查询结果到数组<br />			$row=mysql_num_rows($result); <br />			mysql_query("set names UTF8");<br />	        mysql_close($conn); //关闭数据库连接 <br />	      $this->getInfo(); //调用传递信息的方法.	 <br />	    } <br />	    // 获取信息传递给属性的方法 <br />	    private function getInfo(){ <br />		 <br />	        $this->userName = $this->userInfo["username"]; <br />	        $this->passWord = $this->userInfo["password"];	<br />	        $this->userGrade = $this->userInfo["userGrade"]; <br />	    } <br />	      <br />	    //返回每个属性的public 方法. <br /><br />   public function getRow(){ <br />		<br />	        return $this->row; <br />	    } <br />	    public function getUserName(){ <br />		<br />	        return $this->userName; <br />	    } <br />	      <br />	    public function getPassword(){ <br />	        return $this->passWord; <br />	    } <br />	 <br />	      <br />	    public function getUserGrade(){ <br />	        return$this->userGrade; <br />	    } <br />		<br />		<br />	} <br />		$sql= "select * from userinfo where username='sa' ";<br />	require_once("class_user.php");   <br />	$user= new UserInfo($sql); //创建一个user对象. <br />	    //书写sql<br />	$row= $user->getRow(); <br />	$username= $user->getUserName(); //分别调用方法取得数据 <br />	$password= $user->getPassword(); <br />	$usergrade= $user->getUserGrade(); <br />	  <br />	echo"your name is ".$username."<br>";  //输出数据 <br />	echo"your password is ".$password."<br>"; <br /><br />	echo"your grade is ".$usergrade."<br>"; <br />	echo"your ROW is ".$row."<br>"; <br />	?><br /><br />