Unique IDs that combine a field and sequentially increase
I'm creating a change management log that allows users to submit change orders via a form. To simplify this question, I would like the user to include the project number in their request (this will populate a sheet column titled "Project Number"), then a formula in the sheet (in another column titled "Change ID") will combine the Project Number with a number that sequentially increases based on the previous change order requests that have already been submitted in that same sheet. So if the first change order request for project number 20012 gets submitted, then the Change ID is automatically created to be 20012-1. Then when someone submits another change request for the same project number, it automatically creates a Change ID of 20012-2.
I've gotten myself quite confused researching this, so I'm hoping someone can help out with a formula for me. Thanks!
Help Article Resources
Check out the Formula Handbook template!