The best way to do this is usually with a script. There is an extension that does this: https://support.airtable.com/docs/dedupe-extension. There are also a lot of sample de-duping scripts and some youtube videos on this. (I do not know scripting, and this is one of the few scripts I have in our bases.)

In this case, though, since identifying duplicates is relatively straightforward (which it isn't always), I believe you should also be able to do this with an automation.

The trigger would be "When a form is submitted". Then, the next action would be Find Records based on the ID field of the newly submitted form.

From there, you would add a Conditional Action. If List of Record ID/ Name from Find Record step exists, send an email/slack/etc with links to both the new duplicate and previous record(s).

Hi MLO

Thanks a lot for your reply. 

I've tried to create the Automation now, but for some reason it also sends me an email when there is no duplicate to be found. 

My Automation looks like this (see picture). 

The trigger is 'When a form is submitted' 

1. Action is 'Find Records' Where ID (from the table) contains 'ID' from the form

2. Action (Conditional) is 'If Records List of 'ID' (from Find Records) contains ID (from the form). 

Can you see what causes the issue?

Try the condition: where List of Record IDs is not empty.  

Our miniExtensions form allows you to enforce unique values for certain fields. This way, users would be unable to submit a record containing a duplicate value and instead see an error message.

If you want to prevent duplicate records from ever being entered into Airtable to begin with, your #1 best bet for this is to use Fillout’s advanced forms for Airtable because it lets you prevent duplicate form submissions based on any text fields (or email fields) that you specify.

Fillout offers hundreds of features that Airtable’s native forms don’t offer, including the ability to prevent duplicate form submissions, update Airtable records using a form, create custom PDF files from a form submission, accept payments on forms, display Airtable lookup fields on forms, create new linked records on a form, control access to a form via SSO or email domains or a list of email addresses stored in Airtable, perform math or other live calculations on your forms, collect signatures on a form, create multi-page forms with conditional paths, connect a single form to dozens of external apps simultaneously, add CAPTCHAs to your form, and much more.

I show how to use a few of the advanced features of Fillout on these 2 Airtable podcast episodes:

• Using Fillout to create an eSignature approval process with PDF file creation.
• Using Fillout to create an order entry form with line items.

Hope this helps! If you’d like to hire the best Airtable consultant to help you with anything Airtable-related, please feel free to contact me through my website: Airtable consultant — ScottWorld