这个代码可以改写成一个类吗？

<?php$pdo=new PDO("mysql:host=localhost;dbname=t1","root","");		$id=$_GET["id"];		$stmt=$pdo->prepare("select * from user where username=?");		$stmt->execute(array($id));		$res=$stmt->fetchall();		if($res){			echo "用户名已被占用";		}else{		   echo "可以使用";		}?>

<?php$pdo=new PDO("mysql:host=localhost;dbname=t1","root","");$id=$_GET["id"];$stmt=$pdo->prepare("select * from user where email=?");$stmt->execute(array($id));$res=$stmt->fetchall();if($res){	echo "邮箱已被占用";}else{   echo "可以使用";}?>

<?phpfunction doit($id, $field, $name){		$pdo=new PDO("mysql:host=localhost;dbname=t1","root","");        $id=$_GET["id"];        $stmt=$pdo->prepare("select * from user where ".$field."=?");        $stmt->execute(array($id));        $res=$stmt->fetchall();        if($res){            echo '<span style="color: #FF0000;">'.$name.'</span>已被占用';        }else{           echo "可以使用";        }}doit($id, 'username', '用户名');doit($id, 'email', '邮箱');?>