Primary key? Email?

I am not sure if this is a bubble limitation or if there is a work around. I want to upload a CSV file with employee data and many of them do not have emails but when I attempt to load the file, those without emails trigger a code and cause a failed upload. When I remove all employees without email I am then able to load the CSV. I want to use an employe I.D. (EID) as the key and not the email. Is this possible? If so, what is the common work around?
Thanks in advance for any feedback.

Are you trying to add them as users that can log into your system?

If so, Bubble requires an email. Bubble will also auto-generate a 32-digit unique ID for each user, which serves as its key identifier.