Chapter 3: Database Management

Which of the following statements is true about the figure shown below?

A rental unit can be an apartment or a house; it may not be more than one at the same time.

Specifies whether each supertype occurrence must also be a member of at least one subtype

Completeness Constraints

A Simple attribute with alternative values to indicate the possible subtypes

Disjoint

An instance of the supertype can be only ONE of the subtypes. Subtypes contain a unique subset of the supertype entity set. Also known as non overlapping

Disjoint Rule

Whether an instance of a supertype may simultaneously be a member of two (or more) subtypes

Disjointness Constraints

Data models of an existing database are harder for data modelers to read. (T/F)

False

Generalization is a top-down process. (T/F)

False

In the figure shown below, a rental unit can be both a house and an apartment. (T/F)

False

Packaged data models cause projects to take more time to build. (T/F)

False

Regardless of the business situation, a member of the supertype is always a member of more than one subtype. (T/F)

False

When the total specialization rule is set for a supertype/subtype relationship, one could roughly compare the supertype to an abstract class in object-oriented programming. (T/F)

False

Given the following entities, which of the choices below would be the most complicated? Automobile: VIN, EngineSize, NumberOfDoors, NumberOfPassengers, FuelType, Transmission SUV: VIN, EngineSize, NumberOfPassengers, NoWheelDrive, FuelType, Transmission Truck: VIN, EngineSize, NoWheelDrive, FuelType, Transmission, Payload

One entity type to hold all entities

An instance of the supertype could be more than one of the subtypes

Overlap Rule

A composite attribute whose subparts pertain to different subtypes

Overlapping

Predefined data models Could be universal or industry-specific Universal data model = a generic or template data model that can be reused as a starting point for a data modeling project (also called a "pattern")

Packaged Data Models

The subtype discriminator in the figure below is:

Part_Type

The ________ rule specifies that an entity instance of a supertype is allowed not to belong to any subtype.

Partial Specialization

Supertype partially represents whole data structure. There is an entity outside of the supertype/subtype group. Represented by single line

Partial Specialization Rule

In the figure below, which of the following apply to both OUTPATIENTs and RESIDENT_PATIENTs?

Patient_Name

Which of the following is true of packaged data models?

Relationships are connected to the highest-level entity type in an order that makes sense.

Refers to an attribute of a supertype whose values determine the target subtype(s)

Subtype Discriminator

Which of the following is a generic entity type that has a relationship with one or more subtypes?

Supertype

Supertype represents the entirety of the data structure with no entities left out. Represented by a double line

Total Specialization Rule

Which of the following is a completeness constraint?

Total specialization

A subtype can become a supertype if the subtype has other subtypes beneath it. (T/F)

True

A universal data model is a generic or template data model that can be reused as a starting point for a data modeling project. (T/F)

True

An entity cluster can have a relationship with another entity cluster much the same way that an entity can have a relationship with another entity. (T/F)

True

An entity cluster should focus on some area of interest to some community of users, developers, or managers. (T/F)

True

An entity instance of a subtype represents the same entity instance of the supertype. (T/F)

True

Because a purchased data model is extensive, you begin by identifying the parts of the data model that apply to your data modeling situation. (T/F)

True

Entity clustering is a methodology for grouping one or more entity types and associated relationships into a single abstract entity type. (T/F)

True

In a supertype/subtype hierarchy, attributes are assigned at the highest logical level that is possible in the hierarchy. (T/F)

True

It is easier to share information across organizations if companies in the same industry use the same universal data model as the basis for their organizational databases. (T/F)

True

It is easy to miss the opportunity to visualize future requirements shown in the full data model when using a packaged data model. (T/F)

True

One of the major challenges in data modeling is to recognize and clearly represent entities that are almost the same. (T/F)

True

Packaged data models are meant to be customized. (T/F)

True

Packaged data models can be developed using proven components. (T/F)

True

Specialization is the reverse of generalization. (T/F)

True

Supertype/subtype relationships should not be used when the instances of a subtype participate in no relationships which are unique to that subtype. (T/F)

True

The most important challenge of customizing a purchased data model is determining the business rules that will be established through the data model. (T/F)

True

In the figure below, to which of the following entities are the entities "CAR" and "TRUCK" generalized?

Vehicle

An entity cluster is:

a set of one or more entity types and associated relationships grouped into a single abstract entity type.

The property by which subtype entities possess the values of all attributes of a supertype is called:

attribute inheritance.

An entity cluster can be formed by:

combining a strong entity and its weak entities.

A(n) ________ constraint is a type of constraint that addresses whether an instance of a supertype must also be an instance of at least one subtype.

completeness

A good method for identifying inconsistencies and finding hidden meaning in the customized purchased data model is:

data profiling.

The most important challenge of customizing a purchased data model is:

determining the business rules that will be established through the data model.

The ________ rule specifies that an entity can be a member of only one subtype at a time.

disjoint

A ________ addresses whether an instance of a supertype may simultaneously be a member of two or more subtypes.

disjointness constraint

When identifying the parts of the packaged data model that apply to your organization, one should first start with:

entities

The process of defining a more general entity type from a set of more specialized entity types is called:

generalization

The third step in the data modeling process with a packaged data model is:

map data to be used from package to data in current databases.

All of the following are advantages of packaged data models EXCEPT:

more one-to-one relationships give the data model more flexibility.

In the figure below, a student:

must be a graduate student, an undergraduate, a special student or some other type of student.

In a supertype/subtype hierarchy, each subtype has:

only one supertype.

The ________ rule states that an entity instance can simultaneously be a member of two (or more) subtypes.

overlap

The process of defining one or more subtypes of a supertype and forming relationships is called:

specialization.

In a supertype/subtype hierarchy, subtypes that are lower in the hierarchy inherit attributes from not only their immediate supertype but from all ________ in the hierarchy.

supertypes

The following figure shows an example of:

the overlap rule.

The following figure is an example of:

total specialization

In packaged data models, all subtype/supertype relationships follow the ________ and ________ rules.

total specialization; overlap

A generic or template data model that can be reused as a starting point for a data modeling project is called a(n):

universal data model.

All of the following are steps to using a packaged data model EXCEPT:

utilize all business rules that come with the packaged data model.