Exam 5: Advanced Data Modeling

Explain the two criteria that help a designer in determining when to use subtypes and supertypes.

_____ completeness means that not every supertype occurrence is a member of a subtype.

A _____ is a primary key created by a database designer to simplify the identification of entity instances.

According to the "preferably single-attribute" characteristic of a primary key, the primary key:

A(n) _____ occurs when you have one entity in two 1:M relationships to other entities, thus producing an association among the other entities that is not expressed in the model.

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

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

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

Disjoint subtypes are subtypes that contain nonunique subsets of the supertype entity set.

If one exists, a data modeler uses a _____ as the primary key of the entity being modeled.

Nonoverlapping subtypes are subtypes that contain a(n) _____ subset of the supertype entity set.

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

A weak entity in a strong identifying relationship with a parent entity is normally used to represent a(n) _____ that is represented in the data model as two separate entities.

The completeness constraint can be partial or total.

The function of the primary key is to describe an entity.

Within a specialization hierarchy, every subtype can have _____ supertype(s) to which it is directly related.

Unique values can be better managed when they are _____, because the database can use internal routines to implement a counter-style attribute that automatically increments values with the addition of each new row.

The entity supertype contains common characteristics, and the entity subtypes each contain their own unique characteristics.

Overlapping subtypes are subtypes that contain _____ subsets of the supertype entity set.

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