Automation: Need help with conditional branching expression

[Lindsey_Lindow]

When new rows are added, an automation triggers an action named "NEW TICKET" to set the value of [TICKET#] using the following expression:

CONCATENATE("WC", [_RowNumber])

The table has 4300+ rows and the automation has worked on all rows except for three (On the three affected rows, the cell was left blank).  It's unclear why the bot didn't run those three times and I can't reproduce the issue, so I want to create a second bot using conditional branching that would be something like:

Step 1) On updates, check if [TICKET#] is equal to CONCATENATE("WC", [_RowNumber])

Step 2) If yes, do nothing

Step 3) If no, run Action "NEW TICKET"

I'm having trouble writing the expression for Step 1, as I keep getting the error: "Unable to find column '_RowNumber'"

[Marc_Dillon]

Why not simply give the [TICKET #] column an app formula?

https://help.appsheet.com/en/articles/961507-app-formulas-and-initial-values

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Additionally, you might have a potential for multiple records to get the same ticket number with this setup, if users add new records close to the same time without syncing first. Basing things like these on _RowNumber is not a great idea for this reason, among others. This post is a bit of a tangent, but same basic ideas apply:

https://community.appsheet.com/t/serial-numbers-if-you-must/19325

[Lindsey_Lindow]

Thank you for responding, Marc. The App is set to sync with every change and originally it was an App formula, but I had the exact issue you mentioned, in which different users added new records within seconds of each other, resulting in duplicate ticket numbers.

I have no background in C.S. and am figuring this out as I go, but my train of thought is that the bot won't be triggered until it sees new records, and new records can't exist without row numbers, so I thought having a bot set the value of [TICKET#] would be a way to avoid duplicates because the row numbers are established before the bot sees the new records. I've been using this method for a year and zero duplicates have occurred, so it seems reliable for my needs. (Also, rows are never deleted from the backend)