How to detect duplicated data on Appsheet when user open screen at the same time

[Nattakarn_Girl]

My Appsheet is connected with Google Sheet. I tried to protect duplicated data in Appsheet but

the result isn't good. My key is "Delivery No. = D20220518 and D20220517 ( Auto-generated by Concatenated )

      I have a problem with users recording duplicated data to appointments at the same time ( the detail on my picture ) I figure out that they are opening the screen at the same time ( I saw the data that they logged in on 24/1/2022 on 11.01-11.07 am.) when the first person accepted data, the record will save in google sheet. when the second person accepted data, the record will add a row and save it in different Delivery No. Could you help me find a way to detect duplicated data? please.

[WillowMobileSys]

AppSheet is a distributed multi-user system meaning each user gets their own copy of the app data and then their updates are posted back to the server.  Unfortunately, based on how I understand the app needs to be used, there is absolutely no way to prevent users from submitting the same data at basically the same time.  

The only recourse you have is to use Automation to identify if there is already a duplicate and reject it if one already exists.  You can then send the rejected user a notification and ask them to refresh their app and try again. 

[Nattakarn_Girl]

   Thank you to reply my question. I'm just an amateur. Could you give me a good direction to use Automation to identify this problem? Please.