如何在交易時處理錯誤？

Question

這裏是我的代碼：

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，我的腳本回滾所有查詢時，有一個例外。但是當if ($num_rows['user_id']){是false時它不會回滾。那麼我該如何回滾查詢，並在false的條件下保留錯誤'token is invalid'？

Answer 1

只要拋出一個異常，並像你已經這樣做。但不是一個捕獲聲明有兩個：

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

您的操作順序不好。在驗證令牌之前，您正在對數據庫進行更改。這是不好的安全設計。總是首先驗證所有輸入，然後才進行更改。

其次，獲取令牌的SELECT查詢不需要是事務的一部分。回滾SELECT不會產生影響，因爲這樣的查詢不會更改數據庫。所以我會做

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 
} 

在這種情況下，因爲只有一個查詢可以改變DB，你甚至不需要交易。

Answer 3

容易得多，如果你確保了表中包含的興趣

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(); 
} 

的要求退出值後做更新（）是多餘的也是一樣，可以被刪除。