Move off Oracle PL/SQL without rewriting blind.

PROCEDURE apply_late_fee(p_acct IN NUMBER) IS
  v_due  NUMBER;
BEGIN
  SELECT balance INTO v_due
    FROM accounts WHERE id = p_acct FOR UPDATE;
  IF v_due > 0 AND SYSDATE > due_date(p_acct) THEN
    UPDATE accounts SET balance = v_due * 1.02
     WHERE id = p_acct;
  END IF;
END;

// Behavior: +2% fee if overdue (row-locked)
@Transactional
public void applyLateFee(long acctId) {
  Account a = repo.findByIdForUpdate(acctId);
  if (a.isOverdue(clock) && a.hasBalance())
    a.setBalance(a.getBalance().multiply(LATE_FEE));
}