INFO 3233 PRACTICE QUESTIONS AND VERIFIED
ANSWERS
A _____ is a primary key created by a database designer to simplify the identification of
entity instances. - Answers - surrogate key
An entity cluster is considered "virtual" or "_____" in the sense that it is not actually an
entity in the final ERD. - Answers - abstract
A specialization hierarchy can have _____ level(s) of supertype/subtype relationships. -
Answers - many
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. -
Answers - real-world object
Disjoint subtypes are also known as _____ subtypes - Answers - non-overlapping
Generalization is based on grouping unique characteristics and relationships of the
subtypes. - Answers - false
Implementing nonoverlapping subtypes requires the use of one discriminator attribute
for each subtype. - Answers - false
In which two cases are composite primary keys particularly useful? - Answers - - As
identifiers of composite entities, where each primary key combination is allowed only
once in the M:N relationship.
- As identifiers of weak entities, where the weak entity has a strong identifying
relationship with the parent entity.
Some designs use redundant relationships as a way to simplify the design. - Answers -
true
Surrogate primary keys are especially helpful when there is no _____ key. - Answers -
natural
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. - Answers -
security compliant
The default comparison condition for the subtype discriminator attribute is the _____
comparison - Answers - equality
ANSWERS
A _____ is a primary key created by a database designer to simplify the identification of
entity instances. - Answers - surrogate key
An entity cluster is considered "virtual" or "_____" in the sense that it is not actually an
entity in the final ERD. - Answers - abstract
A specialization hierarchy can have _____ level(s) of supertype/subtype relationships. -
Answers - many
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. -
Answers - real-world object
Disjoint subtypes are also known as _____ subtypes - Answers - non-overlapping
Generalization is based on grouping unique characteristics and relationships of the
subtypes. - Answers - false
Implementing nonoverlapping subtypes requires the use of one discriminator attribute
for each subtype. - Answers - false
In which two cases are composite primary keys particularly useful? - Answers - - As
identifiers of composite entities, where each primary key combination is allowed only
once in the M:N relationship.
- As identifiers of weak entities, where the weak entity has a strong identifying
relationship with the parent entity.
Some designs use redundant relationships as a way to simplify the design. - Answers -
true
Surrogate primary keys are especially helpful when there is no _____ key. - Answers -
natural
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. - Answers -
security compliant
The default comparison condition for the subtype discriminator attribute is the _____
comparison - Answers - equality
