Once you enter data in a table, you can't change the data type of any field to AutoNumber, even if you haven't yet added ...

Once you enter data in a table, you can't change the data type of any field to AutoNumber, even if you haven't yet added data to that field.@Add a new field to the table, and define its data type as AutoNumber. |9 then enters data in the AutoNumber field automatically, numbering the records consecutively starting with 1.@@1@@@1