Do not allow user to submit if value already exisits

Hi All,

I am creating a booking system which allows users to book their delivery / pick up. I have a date and time column as well as a bunch of other data inputs like reference numbers and names etc. When the user tries to book their delivery in how can i get appsheet to now allow the user to select the time they want if that time and “date” is already in the spreadsheet (2 columns). Further to this if it can be done can, i have an enum for times with show every 15 minutes for 24 hours of the day. If that time and date i,e 08/08/2020 7:30am is detected in the spreasheet columns do not show this in the enum - at best do not allow user to input that time (Already booked out)

Thank you

So you need your list of every 15 minutes minus a list of all the times that currently have a delivery.
I do this in an app of mine with interview times. I have a prepopulated table that contains every possible interview time per district and my time field is limited to times that don’t already have a candidate.

Use something like this as your Valid_IF formula:


Its obviously more complicated if you need to look for overlapping time entries


You’re a champion. Works perfectly, thank you very much.

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