// Set up prepared statements transfer from one account to another
$amount = 200;
$payer = 'John White';
$payee = 'Jane Black';
$debit = 'UPDATE savings SET balance = balance - :amount WHERE name = :payer';
$credit = 'UPDATE savings SET balance = balance + :amount WHERE name = :payee';

$pay = $db->prepare($debit);
$pay->bindParam(':amount', $amount);
$pay->bindParam(':payer', $payer);

$receive = $db->prepare($credit);
$receive->bindParam(':amount', $amount);
$receive->bindParam(':payee', $payee);