Avoiding Duplicate Combinations in Access 2007

Hi,

I'd just begun to gain confidence in SQL, when I came across this issue:

I am creating a Table using SQL in Access 2007.
In this table, I want to create a field called ID for student records (Integer data type). I want to create another field called "Months" (INTEGER data type), and want to limit it to values between 1 and 12. Now, since student records would also begin with 1, I am in a fix when the two fields have duplicate combinations.

Any help on this will be much appreciated.

Thanks in Advance.

Thanks Norie.. Maybe I was thinking too much about avoiding duplicates..

And yes, I have looked into the AutoNumber option for ID.

Thanks very much for your help.