Attribute Types

As with entities, attributes can exist at conceptual, logical, and physical levels. An attribute at the conceptual level must be a concept both basic and critical to the business. We do not usually think of attributes as concepts, but depending on the business need, they can be. When I worked for a telecommunications company, Telephone Number was an attribute that was so important to the business that it was represented on a number of conceptual data models.

An attribute on a logical data model represents a business property. Each attribute shown contributes to the business solution and is independent of any technology, including software and hardware. For example, Author Last Name is an attribute because it has business significance regardless of whether records are kept in a paper file or within the fastest database out there. An attribute on a physical data model represents a database column. The attribute Author Last Name might be represented as the column AUTH_LAST_NM within the table AUTH.