Chapter 3 Database Design Flashcards
attribute inheritance.
The property by which subtype entities possess the values of all attributes of a supertype iscalled:A) hierarchy reception.B) class management.C) attribute inheritance.D) generalization.
Supertype
Which of the following is a generic entity type that has a relationship with one or moresubtypes?A) MegatypeB) SupertypeC) SubgroupD) Class
Define one vehicle entity type to hold all entities.
Given the following entities, which of the choices below would be the most complicated?Automobile: VIN, EngineSize, NumberOfDoors, NumberOfPassengers, FuelType, TransmissionSUV: VIN, EngineSize, NumberOfPassengers, NoWheelDrive, FuelType, TransmissionTruck: VIN, EngineSize, NoWheelDrive, FuelType, Transmission, PayloadA) Define one vehicle entity type to hold all entities.B) Define a separate entity type for each entity.C) Define a supertype called vehicle and make each of the entities subtypes.D) Keep only the Truck entity type.
there are attributes that apply to some but not all instances of an entity type
Subtypes should be used when:A) there are attributes that apply to some but not all instances of an entity type.B) supertypes relate to objects outside the business.C) the instances of a subtype do not participate in a relationship that is unique to that subtype.D) a recursive relationship is needed.
specialization
The process of defining one or more subtypes of a supertype and forming relationships iscalled:A) specialization.B) generalization.C) creating discord.D) selecting classes
generalization
The process of defining a more general entity type from a set of more specialized entity typesis called:A) generalizationB) specialization.C) normalization.D) extrapulation.
partial specialization
The ________ rule specifies that an entity instance of a supertype is allowed not to belong toany subtype.A) semi-specializationB) total specializationC) partial specializationD) disjointedness
total specialization
The ________ rule specifies that each entity instance of the supertype must be a member ofsome subtype in the relationship.A) semi-specializationB) total specializationC) partial specializationD) total convergence
Total specialization
Which of the following is a completeness constraint?A) Total specializationB) Partial generalizationC) Total recallD) Partial hybridization
Completeness
A(n) ________ constraint is a type of constraint that addresses whether an instance of asupertype must also be an instance of at least one subtype.A) disjointB) overlapC) completenessD) weak
disjointedness constraint
A ________ addresses whether an instance of a supertype may simultaneously be a memberof two or more subtypes.A) disjointedness constraintB) disjoint ruleC) partial specializationD) total specialization
subtype discriminator
An attribute of the supertype that determines the target subtype(s) is called the:A) determinant.B) subtype decision.C) disjoint indicator.D) subtype discriminator.
overlap
The ________ rule states that an entity instance can simultaneously be a member of two (ormore) subtypes.A) disjointB) overlapC) partial specializationD) total specialization
overlap rule
The subtype discriminator is a composite attribute when there is a(n):A) overlap rule.B) disjoint rule.C) partial specialization.D) full specialization.
only one supertype.
In a supertype/subtype hierarchy, each subtype has:A) only one supertype.B) many supertypes.C) at most two supertypes.D) at least one subtype.
supertypes
In a supertype/subtype hierarchy, subtypes that are lower in the hierarchy inherit attributesfrom not only their immediate supertype but from all ________ in the hierarchy.A) subtypesB) supertypesC) constraintsD) dimensions
a set of one or more entity types and associated relationships grouped into a single abstractentity type.
An entity cluster is:A) a formal method for specifying attributes of related entities.B) a set of one or more entity types and associated relationships grouped into a single abstractentity type.C) a useful way to present data for a small and fairly simple organization.D) a way of developing more granular views of the data model.
combining a strong entity and its weak entities
An entity cluster can be formed by:A) deleting a supertype and its subtype.B) combining metadata.C) combining a strong entity and its weak entities.D) deleting metadata.
require customization
Packaged data models:A) are ready to use right out of the box.B) require customization.C) allow partial specialization.D) cannot be used for most applications.
Relationships are connected to the highest-level entity type in an order that makes sense.
Which of the following is true of packaged data models?A) Relationships are connected to the highest-level entity type in an order that makes sense.B) All subtype/supertype relationships follow the total specialization and disjoint rules.C) No entities on the many sides of a relationship can be weak.D) All weak entities are considered strong.
universal data model
A generic or template data model that can be reused as a starting point for a data modelingproject is called a(n):A) packaged data model.B) universal data model.C) enterprise data model.D) collection data model
essential components and structures are already defined.
Using a packaged data model, projects take less time and cost because:A) less personnel are required.B) essential components and structures are already defined.C) there is more time taken to model the enterprise.D) packaged data models only run in Oracle.
more one-to-one relationships give the data model more flexibility.
All of the following are advantages of packaged data models EXCEPT:A) packaged data models can be built using proven components evolved from cumulativeexperiences.B) projects take less time and cost less.C) the data model is easier to evolve.D) more one-to-one relationships give the data model more flexibility.
utilize all business rules that come with the packaged data model.
All of the following are steps to using a packaged data model EXCEPT:A) identify the parts of the data model that apply to your data modeling situation.B) utilize all business rules that come with the packaged data model.C) rename the identified data elements.D) map data to be used in packages with existing data in the current databases
entities
When identifying the parts of the packaged data model that apply to your organization, oneshould first start with:A) entities.B) attributes.C) primary keys.D) relationships
map data to be used from package to data in current databases
The third step in the data modeling process with a packaged data model is:A) rename identified data elements.B) rename relationships.C) map data to be used from package to data in current databases.D) interview users
data profiling
A good method for identifying inconsistencies and finding hidden meaning in the customizedpurchased data model is:A) data analysis.B) data volume usage analysis.C) user interviews.D) data profiling
determining the business rules that will be established through the data model.
The most important challenge of customizing a purchased data model is:A) getting user buy-in.B) determining the business rules that will be established through the data model.C) implementation.D) user training.
M:N relationships - many-to-many
In packaged data models, strong entities always have ________ between them.A) weak entitiesB) 1:1 relationshipsC) 1:M relationshipsD) M:N relationships
total specialization; overlap
In packaged data models, all subtype/supertype relationships follow the ________ and________ rules.A) partial specialization; disjointB) total specialization; disjointC) total specialization; overlapD) partial specialization; overlap
The business environment has drastically changed since the relational model was firstintroduced in the 1970s. Business relationships are more complex, and organizations must haveways to represent data to represent the complexity. Organizations must be prepared to segmenttheir markets as well as customize their products. The enhanced E-R model has evolved torepresent these changes and also is similar to the object-oriented data model.
Explain why the E-R model needed to be expanded into the enhanced E-R model.
A subtype is an entity which represents data meaningful to the organization. Forexample, an undergraduate student and a graduate student might be a subtype. A supertype is ageneralization of various subtypes and contains attributes which are common to both. Supertypesand subtypes may have relationships with other entities. Also, a subtype inherits the attributes ofits supertype.
Explain the terms subtype and supertype. Discuss the differences between them
Total specialization would be used when you know that there are no other subtypes of asupertype other than those defined. For example, if we only had undergraduate and graduatestudents but no other types of students, then we would use total specialization. However, if therewere students other than graduate and undergraduate, such as just a general student, then wewould want to use partial specialization.
Discuss when one would use total specialization and when one would use partialspecialization
The disjoint rule is used when you wish to specify that an entity instance can only beone type of subtype. For example, if a student could only be a graduate or undergraduate student,but not both. The overlap rule specifies that an entity instance could be one or more subtypes.For example, if an instance of a person supertype could be a faculty member as well as a studentsubtype, then we would use the overlap rule.
Contrast the overlap rule to the disjoint rule
Subtypes that are lower in the hierarchy inherit attributes not only from their immediatesupertype but also from all supertypes higher in the hierarchy all the way to the root
Discuss how attribute inheritance works in a supertype/subtype hierarchy
An entity cluster is a group of entities and relationships which act as one entity. Entityclustering can be thought of as a way to decompose a data model hierarchically, gaining finerand finer views. Entity clusters can interact with other entity clusters just like entities can interactwith each other.
Explain what entity clustering is.
Most organizations can no longer afford to have data models developed in house, bothin terms of labor costs as well as time. As such, the role of data modeler is evolving from artisanto that of engineer. A packaged data model allows one to customize an organization's databaseneeds using a superset of the model needed by the organization
Why are packaged data models gaining popularity?
A packaged data model is quite extensive, so you would begin with the part of the datamodel that you will use for your situation. You would start first with entities, then attributes andthen relationships. The next step is to rename the data elements to terms that are meaningful toyour organization. Since the packaged data model may be used to replace an existing system, thenext step is to map the packaged model to the current database. This mapping will be used laterfor data migration. Perhaps the most challenging step is to determine the business rules for thenew system.
How is the data modeling process different when starting with a purchased solution?Answer:
Patient_Name
In the figure below, which of the following apply to both OUTPATIENTs andRESIDENT_PATIENTs?A) Checkback_DateB) Date_DischargedC) Patient_NameD) XML
Outpatient
In the figure below, which of the following is a subtype of patient?A)OutpatientB) PhysicianC) BedD) Date_Hired
Vehicle
In the figure below, to which of the following entities are the entities "CAR" and "TRUCK"generalized?A) MakeB) VehicleC) ModelD) Price
total specialization.
The following figure is an example of:A) partial specialization.B) completeness.C) total specialization.D) disjointness
partial specialization.
The following figure is an example of:A) partial specialization.B) disjoint completeness.C) total specialization.D) transunion constraint.
must be a graduate student, an undergraduate, a special student or some other type of student
In the figure below, a student:A) must be a graduate student, an undergraduate, a special student or some other type of student.B) must be a graduate student or an undergraduate student.C) must be at least a special student.D) must be a doctoral student.
disjoint
In the figure below, the patient must be either an outpatient or a resident patient. This is anexample of the ________ rule.A) disjointB) specializationC) generalizationD) overlap
subtype discriminator
The following diagram shows:A) total specialization.B) partial specialization.C) the overlap rule.D) subtype discriminator
Part type - A Subtype Discriminator is an attribute of the Supertype that is used to "code" or denote which Subtype an entity is
The subtype discriminator in the figure below is:A) Part_Type.B) Part_No.C) Manufactured Part.D) Location.
the overlap rule.
The following figure shows an example of:A) the disjoint rule.B) the completeness rule.C) the underdog rule.D) the overlap rule
A rental unit can be an apartment, house or just a rental unit; it may not be more than one atthe same time.
Which of the following statements is true about the figure shown below?A) A rental unit must be either an apartment or a house, and cannot be both at the same time.B) A rental unit can be an apartment, house or just a rental unit; it may not be more than one atthe same time.C) A rental unit must be either an apartment or a house, and could be both.D) A rental unit can be an apartment, a house or just a rental unit. It could be both an apartmentand a house at the same time
A rental unit must be either an apartment or a house, and could be both.
Which of the following statements is true about the figure shown below?A) A rental unit must be either an apartment or a house, and cannot be both at the same time.B) A rental unit can be an apartment, house or just a rental unit; it may not be more than one atthe same time.C) A rental unit must be either an apartment or a house, and could be both.D) A rental unit can be an apartment, a house or just a rental unit. It could be both an apartmentand a house at the same time.
A rental unit can be an apartment, a house or just a rental unit. It could be both an apartmentand a house at the same time.
Which of the following statements is true about the figure shown below?A) A rental unit must be either an apartment or a house, and cannot be both at the same time.B) A rental unit can be an apartment, house or just a rental unit; it may not be more than one atthe same time.C) A rental unit must be either an apartment or a house, and could be both.D) A rental unit can be an apartment, a house or just a rental unit. It could be both an apartmentand a house at the same time
supertype/subtype hierarchy.
The following figure shows a:A) disjoint constraint.B) completeness constraint.C) supertype/subtype hierarchy.D) spindle constraint
A person can only be a faculty, student or staff
Which statement is true about the following diagram?A) A person can only be a faculty, student or staff.B) A student can be both an undergraduate and a graduate student at the same time.C) All attributes of person and student are inherited by undergraduate.D) All attributes of graduate are inherited by person.
entity cluster. An entity cluster is a set of one or more entity types and associated relationships
The figure below is an example of a(n):A) supertype/subtype hierarchy.B) hierarchical data model.C) entity cluster.D) column cluster.
FALSE
The following figure is an example of total specialization.
FALSE
The following figure is an example of the overlap rule
TRUE
There are three separate discriminators in the following diagram because of the overlap rule.
Attributes are assigned at the highest logical level that is possible in the hierarchy. Forexample, in the following diagram, one would assign the name to the person supertype so that itcould be shared by as many subtypes as possible
Discuss how attributes are assigned in a supertype/subtype hierarchy.