Exam 5: Advanced Data Modeling

An entity cluster is a "virtual" entity type used to represent multiple entities and relationships in the ERD.

____ relationships occur when there are multiple relationship paths between related entities.

Composite primary keys are particularly useful as identifiers of composite entities,where each primary key combination is allowed only once in the ____ relationship.

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

Non-overlapping subtypes are subtypes that contain a(n)____ subset of the supertype entity set.

The property of ____ enables an entity subtype to inherit the attributes and relationships of the supertype.

From a data modeling point of view,____________________ refer to data whose values change over time and for which you must keep a history of the data changes.

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

The "____" characteristic of a primary key states that: The selected primary key must not be composed of any attribute(s)that might be considered a security risk or violation.For example,using a Social Security number as a PK in an EMPLOYEE table is not a good idea.

In specialization hierarchies with multiple levels of supertype/subtypes,a lower-level supertype inherits all of the attributes and relationships from all of its upper-level subtypes.

____ is a generic entity type that is related to one or more entity subtypes.

Disjoint subtypes are also known as ____________________ subtypes.

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

The property of subtype discriminator enables an entity supertype to inherit the attributes and relationships of the subtype.

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

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

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

An entity cluster is formed by combining multiple interrelated entities into ____.

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

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