Primary Keys in Tables for Web DB in SharePoint

[PaulA]

I am considering putting a backend DB in SharePoint Online. I did a test and it seemed that it is required for primary keys to be numerical. I have had some simple reference tables that didn't use a numerical/autonumber primary key.

Am I missing something or is this correct?

Is there any references for putting an Access database on to Web services and what "rules" there are that might not be present for regular Access?

Thanks.