IT Quiz 5
At the implementation level, the supertype and its subtype(s) depicted in the specialization hierarchy maintain a ____ relationship.
1:1
Partial completeness is symbolized by ____.
A circle over a single line
An entity cluster is formed by combining multiple interrelated entities into ____.
A single abstract entity object
____ is a generic entity type that is related to one or more entity subtypes.
An entity supertype
The extended entity relationship model (EERM) is sometimes referred to as the ____.
Enhanced Entity Relationship Model
The primary key's main function is to uniquely identify a(n) ____ within a table.
Entity instance or row
The default comparison condition for the subtype discriminator attribute is the ____ comparison.
Equality
A ____ 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.
Fan Trap
____ keys work with primary keys to properly implement relationships in the relational model.
Foreign
____ is the bottom-up process of identifying a higher-level, more generic entity supertype from lower-level entity subtypes.
Generalization
The property of ____ enables an entity subtype to inherit the attributes and relationships of the supertype.
Inheritance
Composite primary keys are particularly useful as identifiers of composite entities, where each primary key combination is allowed only once in the ____ relationship.
M:N
A specialization hierarchy can have ____ level(s) of supertype/subtype relationships.
Many
A ____ key is a real-world, generally accepted identifier used to uniquely identify real-world objects.
Natural
Surrogate primary keys are especially helpful when there is no ____ key.
Natural
If one exists, a data modeler uses a ____ as the primary key of the entity being modeled.
Natural Identifier
The "____" characteristic of a primary key states that: The PK should not have embedded semantic meaning. An attribute with embedded semantic meaning is probably better used as a descriptive characteristic of the entity rather than as an identifier.
Non-intelligent
Overlapping subtypes are subtypes that contain ____ subsets of the supertype entity set.
Non-unique
Within a specialization hierarchy, every subtype can have ____ supertype(s) to which it is directly related.
Only One
The preferred placement for a foreign key when working with a 1:1 relationship is to ____.
Place a foreign key in one of the entities
One important inheritance characteristic is that all entity subtypes inherit their ____ key attribute from their supertype.
Primary
The most important characteristic of an entity is its ____ key, used to uniquely identify each entity instance.
Primary
____ relationships occur when there are multiple relationship paths between related entities.
Redundant
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.
Security Compliant
The ____ depicts the arrangement of higher-level entity supertypes (parent entities) and lower-level entity subtypes (child entities).
Specialization Hierarchy
The relationships depicted within the ____ are sometimes described in terms of "is-a" relationships.
Specialization Hierarchy
A(n) ____ is the attribute in the supertype entity that determines to which entity subtype each supertype occurrence is related.
Subtype Discriminator
____ data refer to data whose values change over time and for which you must keep a history of the data changes.
Time Variant
Non-overlapping subtypes are subtypes that contain a(n) ____ subset of the supertype entity set.
Unique
The "____" characteristic of a primary key states that: The PK must uniquely identify each entity instance. A primary key must be able to guarantee unique values. It cannot contain nulls.
Unique Values
