Analyzing Data › Defining Entity Types, Relationships, and Attributes › Finding Different Kinds of Entity Types

Finding Different Kinds of Entity Types

An entity is a thing of fundamental relevance to the enterprise about which data is kept. The definition of an entity suggest that entities can only be tangible objects, such as CUSTOMER and PRODUCT. This is not the case. The intangible objects are also of interest to the business.

Conceptual entity types, such as COST CENTER and LEDGER ENTRY, are used to capture data about less tangible concepts of interest to the business.

Active entity types, such as LECTURE ATTENDANCE and EQUIPMENT BREAKDOWN, are used to represent information about activities that take place.

Active and conceptual entity types are more difficult to identify than tangible entity types but are no less important in determining all the entity types of interest to the business. A business model does not need to include entity types in all three categories, but remember that there are entity types other than those representing a set of purely physical things.

You discover entity types by identifying the things acted on by business activities by an examination of current data and by considering subject areas and other entity types.

Note: For more information, see Building the Analysis Model.

Each primitive subject area can be expected to have a subject, or central entity type; for example, CUSTOMERS has CUSTOMER as its central entity type.

Entities are dependent or independent:

• Dependent entities
• Order items cannot exist independently of an order, and an order in turn depends on the existence of a customer.
• Dependent entity types further describe an entity type or associate entities together.
• DELIVERY POINT adds further detail to a customer and therefore be described as characteristic.
• ORDER ITEM associates ORDER and PRODUCT and so named associative.
• Independent entities
• Entities that exist externally to the enterprise are independent (CUSTOMER, for example).

The distinction between these categories of entity types are made explicitly and is not stored in a CA Gen model.