#deduct from the transferred account

$update = $DBH->prepare("UPDATE USER SET BALANCE = BALANCE - ? WHERE USERNAME = ?");
$update->execute($amount, $user);
$up = $update->finish();

#add to the receiving account
$update1 = $DBH->prepare("UPDATE USER SET BALANCE = BALANCE + ? WHERE USERNAME = ?");
$update1->execute($amount, $user);
$up1 = $update1->finish();