If you make changes to several Records, you can write them back to the database using a unit-of-work Transaction. You can plan for Records to be inserted, updated, and deleted, in whatever order you like, and then execute the entire transaction plan at once. Exceptions will cause a rollback.
<?php
// create a transaction
$transaction = $atlas->newTransaction();
// plan work for the transaction
$transaction->insert($record1);
$transaction->update($record2);
$transaction->delete($record3);
// or persist an entire record and its relateds
$transaction->persist($record4);
// execute the transaction plan
$success = $transaction->exec();
if ($success) {
echo "The Transaction succeeded!";
} else {
// get the exception that was thrown in the transaction
$e = $transaction->getException();
// get the work element that threw the exception
$work = $transaction->getFailure();
// some output
echo "The Transaction failed: ";
echo $work->getLabel() . ' threw ' . $e->getMessage();
}