PDO会知道mysql是否崩溃吗？

Question

Forgive me if this is a silly question, but I'm in a difficult situation.

does this:

$query = "SELECT `av`.`UUID`, `pay`.`amount`, `pay`.`id`
      FROM `2starsglobal`.`avatars` AS av
      RIGHT JOIN `payments` AS `pay` ON `av`.`id` = `pay`.`avatarId`
      WHERE `pay`.`payed` = 0 AND `pay`.`verificationPending` = 0
      ORDER BY `pay`.`id` ASC
      LIMIT 0, 14";

$stmt = $db->query($query);

echo 'SUCCESS';

$payments = "";

while($row = $stmt->fetch(PDO::FETCH_NUM))
{
    $payments .= ",{$row[0]},{$row[1]},{$row[2]}";
    //echo ',', $row[0],',', $row[1],',', $row[2];
    $query = "UPDATE `payments` SET `verificationPending`=1 WHERE `id`={$row[2]}"; 
}

try
{
    $db->query($query)->closeCursor();
}
catch(PDOException $e)
{
    return;
}

echo $payments;

guarantee that php will handle the case scenario bellow?

We have a payments system for a game, last time we put it out for testing, mysql settings for allocated memory weren't correct, so the db was refusing connections and didn't run the queries as it should, or at least some of them. So the result was, the paid flag in payments table not getting set and payments to be made over and over.

Now this chunk of code up there is what follows the query and a SUCCESS message ( for communication ) my idea is if mysql crashes or fails in anyway, not to display the payments that should be made. Will the chunk above work in all cases?

Hope i made myself clear and ty

edit: The code above was written mostly for demonstration, it's not correct code, as I noticed a bit late. But that shouldn't bother you because the original question is. If PDO will handle db crashes and all the rest.

my idea is for each Successfully updated row, to echo that particular payment, and that's not what the code above does. pretty messed up.

MORE EDITS

As you'll notice, I'm eager to get an answer about how safe I am. (I hope it'll have states and facts for the reason why i'm safe or why not) So here it is, what I will probably keep as my code, unless told other wise. Should I feel safe with this?

$query = "SELECT `av`.`UUID`, `pay`.`amount`, `pay`.`id`
      FROM `2starsglobal`.`avatars` AS av
      RIGHT JOIN `payments` AS `pay` ON `av`.`id` = `pay`.`avatarId`
      WHERE `pay`.`payed` = 0 AND `pay`.`verificationPending` = 0
      ORDER BY `pay`.`id` ASC
      LIMIT 0, 14";

$stmt = $db->query($query);

$payments = $stmt->fetchAll(); 

$query = "UPDATE `payments` SET `verificationPending`=1 WHERE "; 

foreach($payments as $payment)
{
     $query .= "`id`={$payment[2]} AND "; 
}

$query = substr($query, 0, strlen($query-5));

try
{
    $db->beginTransaction();

    $db->query($query)->closeCursor();

    $db->commit();
}
catch(PDOException $e)
{
    $db->rollBack();
    return;
}

echo "SUCCESS"; 

foreach($payments as $payment)
{
   echo ",{$payment[0]},{$payment[1]},{$payment[2]}";
}

Answer 1

It may not be the solution your looking for but you should always be checking your code as you go. In this instance you want to return success if the record exists...

$query = '...';
$stmt = $db->query($query);

if($stmt === false)
    // Query failed to execute

while($row = $db->fetch(PDO::FETCH_NUM))
{
    ...
}

$stmt = $db->query($query);
if($stmt === false)
    // Update failed

$stmt->closeCursor();
// NOW you can echo

http://php.net/manual/en/pdo.query.php (PDO returns boolean false if it fails to query)