PDO事务机制和错误抛出

<?php
header('content-type:text/html;charset=utf-8');
$pdo=new PDO('mysql:host=localhost;dbname=user2','root','');

$pdo->exec('set names utf8');
$pdo->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
$pdo->beginTransaction();
try{
    $sql="insert into t5(name,num) values('好的','88')";
    $smt=$pdo->prepare($sql);
    $smt->execute();

    $sql="insert into t5l(name,num) values('对的','66')";
    $smt=$pdo->prepare($sql);
    $smt->execute();

    $pdo->commit();  //无错误提交

}catch(PDOException $e){
    $pdo->rollBack(); //有错误撤销
};


?>