ITC 555 Chapter Notes - Chapter 5: Bring Your Own Device, Abstract And Concrete, Cengage Learning
Document Summary
Pks to uniquely identify each entity instance: discuss natural keys, primary keys, and surrogate keys, examine the primary key guidelines that specify the pk characteristics. Pks must be unique, non-intelligent, they do not change over time, they are ideally composed of a single attribute, they are numeric, and they are security compliant: finally, contrast the use of surrogate and composite primary keys. An entity supertype is a generic entity type that is related to one or more entity subtypes, where the entity supertype contains the common characteristics and the entity subtypes contain the unique characteristics of each entity subtype. An entity subtype is a more specific entity type that is related to an entity supertype, where the entity supertype contains the common characteristics and the entity subtypes contain the unique characteristics of each entity subtype. A specialization hierarchy depicts the arrangement of higher-level entity supertypes (parent entities) and lower-level entity subtypes (child entities).
