PHP transaction managers

bank_transaction_manager.php

<?php
$btm = new BankTransactionManager($transaction);

// create entry (Account, Entry Type)
$e = $btm->createEntry("Gold.Gold");
$e->setUserId($user_id);
$e->addGold($gold_amount);
$btm->addEntry($e);

$e = $btm->createEntry("ServerGold.Gold");
$e->setUserId(ENTITY_SERVER);
$e->subtractGold($gold_amount);
$btm->addEntry($e);

try {
     $btm->execute();
}
catch (Exception $e) {
     throw $e;
}
?>

for_update.sql

SELECT "columns" FROM "table" WHERE "criteria" FOR UPDATE;