Booking document need Help

Hello Everyone,

I have a small issue right now, I am using an excel sheet in order to take bookings for a restaurant in my hotel,

The event is for Ramadhan so we are looking to do some volume business, in order to do so, i created a sharepoint with the excel sheet on onedrive so everyone in the hotel is able to book a place,

So here is the problem, the people are now overbooking some dates because 1. they are no checking the availability calendar

So I aam seeking your help and knowledge to be able to block a day for booking, how could I implement it ?

So far the only Idea I had would be to remove the date that acts as a booking code, in my sumif formula, but I actually would like to not allow them to input the booking code, if there is any way,

The other thing That i thought bu would be quite a tedious task would be to just delete any day in the calendar.

But I am worry that it would not restrain people to actually input a reservation and play dumb once its done.

I am joining now the file in question so you can have a look at it.

Wishing you a wonderful day

Kenji Booking Ramadhan Ballroom.xlsx

You can start by using named tables as I did for you.

Actually i found a better solution its to use a drop down menu with the data validation tool, i can now manage the booking codes and remove them if needed to prevent overbooking a specific date by removing the date from the drop down menu. Voila