pdo update operation in php

try {
$pdo = new PDO('mysql:dbname=php','root','root');
} catch (PDOException $e) {
    exit($e->getMessage());
}

$sql = "UPDATE user SET email=:email WHERE user_id=:user_id";

if($stmt = $pdo->prepare($sql)) {

$param = ['email'=>'lwt@qq.com','user_id'=>5];
    //绑定参数到SQL语句对象并执行
    if ($stmt -> execute($param)){
        //rowCount()返回更新的数量,如果大于0表示有记录被更新啦
        if ($stmt->rowCount()>0) {
            echo '成功更新了'.$stmt->rowCount().'条记录';
        } else {  //等于0表示没有记录被更新
            echo '没有记录被更新';
        }
    } else { //执行失败的信息
        print_r($stmt->errorInfo());
        exit();
    }
} else {  //$stmt语句对象创建失败
  print_r($pdo->errorInfo());
  exit();
}