A primary key is a field or fields in your table, not a record. There are
lots of opinions on what type of field or fields to use. I almost always add
an Autonumber primary key field to tables.
Every record in the table should have a Primary Key. This is one field (or
more than one, up to ten fields) which uniquely identifies the record: only
one record in the table can have that value of the PK. It also must be
non-Null.
Could you explain the current structure of your table, and just what it is
that you are trying to accomplish?