如何在交易时处理错误？

Question

这里是我的代码：

try { 
    $dbh_con->beginTransaction(); 

     $stmt1 = $dbh_conn->prepare("UPDATE activate_account_num SET num = num + 1"); 
     $stmt1->execute(); 

     $stmt2 = $dbh_con->prepare("SELECT user_id FROM activate_account WHERE token = ?"); 
     $stmt2->execute(array($token)); 
     $num_rows = $stmt2->fetch(PDO::FETCH_ASSOC); 

     if ($num_rows['user_id']){ 
      $_SESSION['error'] = 'all fine'; 

     } else { 
      $_SESSION['error'] = 'token is invalid'; 
     } 

    $dbh_con->commit(); 

    header('Location: /b.php'); 
    exit(); 

} catch(PDOException $e) { 

    $dbh_con->rollBack(); 

    $_SESSION['error'] = 'something is wrong'; 
    header('Location: /b.php'); 
    exit(); 
} 

正如你看到的，我的脚本回滚所有查询时，有一个例外。但是当if ($num_rows['user_id']){是false时它不会回滚。那么我该如何回滚查询，并在false的条件下保留错误'token is invalid'？

Answer 1

只要抛出一个异常，并像你已经这样做。但不是一个捕获声明有两个：

try { 
    $dbh_con->beginTransaction(); 

     $stmt1 = $dbh_conn->prepare("UPDATE activate_account_num SET num = num + 1"); 
     $stmt1->execute(); 

     $stmt2 = $dbh_con->prepare("SELECT user_id FROM activate_account WHERE token = ?"); 
     $stmt2->execute(array($token)); 
     $num_rows = $stmt2->fetch(PDO::FETCH_ASSOC); 

     if ($num_rows['user_id']){ 
      $_SESSION['error'] = 'all fine'; 

     } else { 
      throw new \Exception('token is invalid'); 
     } 

    $dbh_con->commit(); 

    header('Location: /b.php'); 
    exit(); 

} catch(PDOException $e) { 

$dbh_con->rollBack(); 

$_SESSION['error'] = 'something is wrong'; 
header('Location: /b.php'); 
exit(); 
} catch(Exception $e) { 

    $dbh_con->rollBack(); 

    $_SESSION['error'] = 'token is invalid'; 
    header('Location: /b.php'); 
    exit(); 
} 

Answer 2

您的操作顺序不好。在验证令牌之前，您正在对数据库进行更改。这是不好的安全设计。总是首先验证所有输入，然后才进行更改。

其次，获取令牌的SELECT查询不需要是事务的一部分。回滚SELECT不会产生影响，因为这样的查询不会更改数据库。所以我会做

try{ 
    select token 
    if token is not found, set error and exit 

    begin transaction 
    update active_account_num 
    ...other queries? 
    end transaction and commit 

    set success message, set header & exit 
}catch{ 
    rollback 
    set error message, set header & exit 
} 

在这种情况下，因为只有一个查询可以改变DB，你甚至不需要交易。

Answer 3

容易得多，如果你确保了表中包含的兴趣

try { 
    $stmt2 = $dbh_con->prepare("SELECT user_id FROM activate_account WHERE token = ?"); 
    $stmt2->execute(array($token)); 
    $num_rows = $stmt2->fetch(PDO::FETCH_ASSOC); 

    if ($num_rows['user_id']){ 
     $dbh_con->beginTransaction(); 
     $stmt1 = $dbh_conn->prepare("UPDATE activate_account_num SET num = num + 1"); 
     $stmt1->execute(); 

     $_SESSION['error'] = 'all fine'; 
     $dbh_con->commit(); 

    } else { 
     $_SESSION['error'] = 'token is invalid'; 
     /* no transaction here, nothing to rollback */ 
    } 

    header('Location: /b.php'); 
    exit(); 

} catch(PDOException $e) { 

    $dbh_con->rollBack(); 

    $_SESSION['error'] = 'something is wrong'; 
    header('Location: /b.php'); 
    exit(); 
} 

的要求退出值后做更新（）是多余的也是一样，可以被删除。