lol, my mistake. I forgot the line 5 with the discount...
ps.setByte(5, discountInPercentage);
final Instant startTime = Instant.now();
ps.setInt(1, itemInstance.getObjectId());
ps.setLong(2, pricePerUnit);
ps.setTimestamp(3, Timestamp.from(startTime));
ps.setByte(4, durationInDays);
ps.setByte(5, discountInPercentage);
ps.executeUpdate();