Avoid duplicate entry while uploading csv file

[Sajinjs07]

In Appsheet for bulk upload from csv file... how we can allow only upload new entry and block existing file to avoid duplicate ? I tried using valid if expression. From the row i don't want to copy if business name is already available. 

NOT(IN([_THIS], SELECT(VENDORS[BUSINESS NAME], [VENDOR_ID] <> [_ThisRow].[VENDOR_ID])))

But get stuck if duplicate entry available in csv file. Please advise.

[Joseph_Seddik]

For a similar need, I handled duplicates after importation. You can for example create a slice with:

COUNT(FILTER("Vendors", [vendorID] = [_ThisRow].[vendorID])) > 1

I created a "Duplicate Records" view on this slice and with inline actions, I give the user the options to either delete the record or to acknowledge it as not duplicate. If you are sure and you don't need the user's intervention, you can just remove these duplicates with automation following the importation.

[AleksiAlkio]

One workaround I have used when most of the data contains duplicates.. first import the data into a temporary table with CSV, then trigger a webhook/Bot with the latest imported row because you can filter the data automatically if the row already exists. Then finally delete all temporary rows with the webhook/Bot.