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

$pay = $db->stmt_init();
if (!$pay->prepare($debit)) {
    $error = $pay->error;
}
$pay->bind_param('is', $amount, $payer);

$receive = $db->stmt_init();
if (!$receive->prepare($credit)) {
    $error = $receive->error;
}
$receive->bind_param('is', $amount, $payee);