Exam 5: Advanced Data Modeling

Specialization is the top-down process of identifying lower-level,more specific entity subtypes from a higher-level entity supertype.

Implementing overlapping subtypes requires the use of one discriminator attribute for each subtype.

Entity supertypes and subtypes are organized in a specialization hierarchy.

The purpose of a(n)is to simplify an entity-relationship diagram (ERD)and thus enhance its readability.

An entity cluster is considered "virtual" or " " in the sense that it is not actually an entity in the final ERD.

data refer to data whose values change over time and for which one must keep a history of the data changes.

Which of the following is a specialization hierarchy disjoint constraint scenario in case of partial completeness?

A(n)is the attribute in the supertype entity that determines to which entity subtype each supertype occurrence is related.

The depicts the arrangement of higher-level entity supertypes (parent entities)and lower-level entity subtypes (child entities).

Implementing nonoverlapping subtypes requires the use of one discriminator attribute for each subtype.

While using a surrogate key,one must ensure that the candidate key of the entity in question performs properly through the use of the " " and "not null" constraints.

A partial completeness constraint is represented by .

The most important characteristic of an entity is its key,used to uniquely identify each entity instance.

Subtypes that contain nonunique subsets of the supertype entity set are known as subtypes.

is the bottom-up process of identifying a higher-level,more generic entity supertype from lower-level entity subtypes.

The " " characteristic of a primary key states that the primary key should not have embedded semantic meaning.

Specialization is based on grouping characteristics and relationships of the subtypes.

To model time-variant data,one must create a new entity in an M:N relationship with the original entity.

Usually,a data modeler uses a natural identifier as the of the entity being modeled,assuming that the entity has a natural identifier.

One important inheritance characteristic is that all entity subtypes inherit their key attribute from their supertype.