Lucky draw booking system

[Isaiah1]

I would like to create a booking form on ServiceNow. The only catch is that I would like it to have a lucky draw, or random draw function such that if a few people have selected the same time slot, the system will do a random allocation to one person. 

[jcmings]

How long of a gap is there between selecting the timeslot and submitting? 

[Isaiah1]

We have a monthly cut-off for bookings:

• All advance bookings must be made on or before the 10th of each month for the 2 slots available per day in the following month.
• If there are more advance bookings than boats available for a particular date, the allocation will be performed by a computerized random draw. Random draw will be done on the 10th of every month.

[jcmings]

I don't understand why you would want to build this in the way you are describing. It sounds like a bad user experience. So the user would book an appointment before the 10th, then find out their appointment is cancelled (due to overbooking), and then have to scramble to book another appointment for the current month before the cut-off date? If the user missed that, they would have to book an appointment for a full month in advance -- and there's nothing to say this random drawing doesn't cancel their future appointment again. 

Instead, I would recommend you simply limit the number of appointments per timeslot. If there are no appointments remaining, the timeslot cannot be booked.

[Isaiah1]

Thanks for the feedback! I agree! Ideally I would prefer it to be limited rather than random. but the Process Owner wants to keep it that way. I am also trying to push this away as a design approach.