Learn how to add and remove Primary Keys from an Access database table. The primary key's purpose is to promptly associate data from multiple tables and combine that data.

The Unique Key column is set for the primary key of the CompanyCategory table (CompanyCatID). What that means is that when you delete a record, you will only delete one record at a time.

Can you do a foreign key within a single table, though? I've only ever seen foreign key constraints tying a field in one table to a field in another table.

For Higher Computing Science, revise the use of primary and foreign keys and the difference between flat file and relational databases.