Autofill Check if Unique?
So I have a field that's creates a UserID automatically based on the persons first and last name. e.g. James Smith would auto fill the UserID box with JSMITH - This works perfectly
The Problem I have here is this box needs to be Unique, BUT the odds of us only ever having one JSMITH is slim.
I want to run a script that will check if there are previous JSMITH's and if so then add a number to the end so creating JSMITH1, then recheck if JSMITH1 already exists make it JSMITH2 and so on and so on till it hit's a Unique ID
I have the script in the image but lack the appropriate command to make it work
Can anybody help with this?