Microsoft Office® Access 2007 Inside Out

Changing the Primary Key

Article 1, “Designing Your Database Application,” on the companion CD discusses the need to have one or more fields that provide a unique value to every row in your table. This field or group of fields with unique values is identified as the primary key. If a table doesn’t have a primary key, you can’t define a relationship between it and other tables, and Access 2007 has to guess how to link tables for you. Even if you define a primary key in your initial design, you might discover later that it doesn’t actually contain unique values. In that case, you might have to define a new field or fields to be the primary key.

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