I have an Excel Spreadsheet that is being updated daily and would like to map that spreadsheet to a feature class. The spreadsheet has an ID field in it (#09-09, etc.) . . . but can I create an ID field in the Feature Class table to Join with or will the data types prevent me from doing that?
You can add a field to your table to match and in Pro, there is even a field calculator autoincrement ..
You can even snag the field calculator code here.
Calculate Field Python examples—Data Management toolbox | ArcGIS Desktop
in the ...
Accumulative and sequential calculations
section