Analyzing Data › Defining Entity Types, Relationships, and Attributes › Defining Entity Types › Entity Type Description

Entity Type Description

The entity type description is a block of text that explains the entities of the entity type. A description never includes a layout of the detailed data that is recorded for each entity type.

You can specify the following kinds of descriptive information about an entity type:

• Precise and concise definition, preferably in terminology that is commonly used in the business
• This include:
  • Indication of exactly what the entity is (named the scope)
  • How it is distinguished from entities of other entity types (named the qualification).
• The qualification is used to exclude things that are of no interest to the business.
• The names of relationships and other entity types probably appear in the definition, but you should not merely respecify the Entity Relationship Diagram in words. For example, the definition of the entity type customer is:

  An individual or organization (scope) that purchases (qualifying relationship) products (qualifying entity type) marketed by (qualifying relationship) a division (qualifying entity type).

• Examples of the entity type, if desired
• Any integrity constraints that are associated with entities of the type being described.

  Note: Integrity constraints are discussed in Additional Data Modeling Topics.