Exam 5: Advanced Data Modeling

The main concern with redundant relationships is that they remain across the model.

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

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 violation.

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.

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

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

Within a specialization hierarchy, a supertype can exist only within the context of a subtype.

Surrogate primary keys are especially helpful when there is no key.

At the implementation level, the supertype and its subtype(s) depicted in the specialization hierarchy maintain a 1:1 relationship.

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

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

A partial completeness constraint is represented by .

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

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

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

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

Entity supertypes and subtypes are organized in a specialization hierarchy.

A specialization hierarchy can have level(s) of supertype/subtype relationships.

The default comparison condition for the subtype discriminator attribute is the comparison.