Ch 3-6 Quiz Answers - Flashcards

question

_____ relationships can be implemented by creating a new entity in 1:M relationships with the original entities.

answer

M:N

question

The DIFFERENCE operator subtracts one table from the other

answer

True

question

In a natural join, the column on which the join was made occurs twice in the new table.

answer

False

question

A _____ is any key that uniquely identifies each row.

answer

superkey

question

The ____ is actually a system-created database whose tables store the user/designer-created database characteristics and contents

answer

system catalog

question

The order of the rows and columns is important to the DBMS

answer

False

question

The ____ relationship should be rare in any relational database design

answer

1:1

question

Only a single attribute, not multiple attributes, can define functional dependence

answer

False

question

If the attribute (B) is functionally dependent on a composite key (A) but not on any subset of that composite key, the attribute (B) is fully functionally dependent on (A).

answer

True

question

You can think of a table as a persistent representation of a logical relation.

answer

True

question

A null is created when you press the Enter key or the Tab key to move to the next entry without making a prior entry of any kind.

answer

True

question

The DIVIDE operation uses one single-column table (e.g., column "a") as the divisor and one two-column table (e.g., columns "a" and "b") as the dividend.

answer

True

question

Referential _____ dictates that the foreign key must contain values that match the primary key in the related table, or must contain null.

answer

Integrity

question

RDBMSs enforce integrity rules automatically.

answer

True

question

A relationship is an association between _____.

answer

entities

question

Relationships between entities always operate in one direction

answer

False

question

A ____ attribute is one that cannot be subdivided

answer

simple

question

When the specific cardinalities are not included on the diagram in Crow's Foot notation, cardinality is implied by the use of _____.

answer

symbols

question

The entity relationship model uses the associative entity to represent a(n) _____ relationship between two or more entities.

answer

M:N

question

An entity is said to be _____-dependent if it can exist in the database only when it is associated with another related entity occurrence.

answer

existence

question

The Crow's foot symbol with two vertical parallel lines indicates ___ cardinality.

answer

(1,1)

question

A weak relationship exists if the primary key of the related entity contains at least one primary key component of the parent entity.

answer

False

question

Ideally, an entity identifier is composed of ___ attribute(s)

answer

one

question

Connectivities and cardinalities are established by concise statements known as business rules.

answer

True

question

In the Chen and Crow's Foot notations, an entity is represented with a rectangle containing the entity's name.

answer

True

question

In the entity relationship diagram (ERD), cardinality is indicated using the _____ notation, where max is the maximum number of associated entities and min represents the minimum number of associated entities.

answer

(min, max)

question

In a 1:M relationship, to avoid the possibility of referential integrity errors, the data of the "1" side must be loaded first.

answer

True

question

Nonoverlapping subtypes are subtypes that contain a(n) _____ subset of the supertype entity set.

answer

unique

question

Generalization is based on grouping unique characteristics and relationships of the subtypes.

answer

False

question

A _____ key is a real-world, generally accepted identifier used to uniquely identify real-world objects.

answer

natural

question

The most important characteristic of an entity is its _____ key, used to uniquely identify each entity instance.

answer

primary

question

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

answer

False

question

Some designs use redundant relationships as a way to simplify the design.

answer

True

question

A subtype contains attributes that are common to all of its supertypes

answer

False

question

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

answer

primary

question

Overlapping subtypes are subtypes that contain a unique subset of the supertype entity set.

answer

False

question

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

answer

True

question

Which of the following is a specialization hierarchy overlapping constraint scenario in case of partial completeness?

answer

Supertype has optional subtypes

question

If one exists, a data modeler uses a _____ as the primary key of the entity being modeled.

answer

natural identifier

question

In specialization hierarchies with multiple levels of supertype and subtypes, a lower-level subtype can inherit only a few of the attributes and relationships from its upper-level supertypes.

answer

False

question

Specialization is the top-down process of identifying lower-level, more specific entity subtypes from a higher-level entity supertype.

answer

True

question

Normalization represents a micro view of the entities within the ERD.

answer

True

question

Normalization produces a lower normal form

answer

False

question

Converting a database format from 1NF to 2NF is a complex process

answer

False

question

A determinant is any attribute whose value determines other values within a column.

answer

False

question

A(n) _____ exists when there are functional dependencies such that Y is functionally dependent on X, Z is functionally dependent on Y, and X is the primary key.

answer

Transitive dependency

question

In the context of partial dependencies, data redundancies occur because every row entry requires duplication of data.

answer

True

question

A table is in fourth normal form if it is in third normal form and has no independent multivalued dependencies.

answer

True

question

Normalization is a very important database design ingredient, and the highest level is always the most desirable.

answer

False

question

A _____ derives its name from the fact that a collection of multiple entries of the same type can exist for any single key attribute occurrence.

answer

repeating group

question

1NF, 2NF, and 3NF are _____

answer

normalization stages

question

Repeating groups must be eliminated by ensuring that each row defines a single entity.

answer

True

question

Denormalization produces a lower normal form

answer

True

question

The combination of normalization and ER modeling yields a useful ERD, whose entities can be translated into appropriate relationship structures.

answer

False

question

If a table has multiple candidate keys and one of those candidate keys is a composite key, the table can have based on this composite candidate key even when the primary key chosen is a single attribute.

answer

partial dependencies

question

To generate a surrogate key, Microsoft Access uses a(n) ____ data type.

answer

AutoNumber

question

Dependency diagrams are very helpful in getting a bird's-eye view of all the relationships among a table's attributes.

answer

True

question

An attribute that is part of a key is known as a(n) ______ attribute.

answer

prime

question

From a structural point of view, 2NF is better than _____.

answer

1NF

question

The CUSTOMER table's primary key is CUS_CODE. The CUSTOMER primary key column has no null entries, and all entries are unique. This is an example of _____ integrity.

answer

entity

question

A _____ contains at least all of the attribute names and characteristics for each table in the system.

answer

data dictionary

question

Another name for a composite entity is a(n) _____ entity

answer

bridge

question

A _____ key can be described as a minimal superkey, a superkey without any unnecessary attributes.

answer

candidate

question

_____ are especially useful when you are trying to determine what values in related tables cause referential integrity problems.

answer

Outer joins

question

When you define a table's primary key, the DBMS automatically creates a(n) _____ index on the primary key column(s) you declared.

answer

unique

question

According to Codd's _____ rule of relational database, "Application programs and ad hoc facilities are logically unaffected when changes are made to the table structures that preserve the original table values (changing order of columns or inserting columns)."

answer

logical data independence

question

_____ databases reflect the ever-growing demand for greater scope and depth in the data on which decision support systems increasingly rely.

answer

data warehouse

question

If you have 3 different transitive dependencies, ___ different determinant(s) exist.

answer

three

question

Dependencies based on only a part of a composite primary key are known as _____ dependencies.

answer

partial

question

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.

answer

Security-compliant

question

The "_____" characteristic of a primary key states that the primary key must uniquely identify each entity instance, must be able to guarantee unique values, and must not contain nulls.

answer

unique values

question

Partial completeness constraint is represented by

answer

a single horizontal line under a circle

question

According to the "preferably single-attribute" characteristic of a primary key, the primary key:

answer

should have the minimum number of attributes possible

question

____ keys work with primary keys to properly implement relationships in the relational model

answer

Foreign

question

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

answer

An entity supertype

question

A primary key's main function is to uniquely identify a(n) ___ within a table

answer

entity instance or row

question

Complex _____ requirements may dictate data transformations, and they may expand the number of entities and attributes within the design.

answer

information

question

The decision to store _____ attributes in database tables depends on the processing requirements and the constraints placed on a particular application.

answer

derived

question

A ____ attribute can be further subdivided to yield additional attributes.

answer

Composite

question

A ____ entity has a primary key that is partially or totally derived from the parent entity in the relationship

answer

weak

question

The existence of a mandatory relationship indicates that the minimum cardinality is 0 or 1 for the mandatory entity

answer

False

question

Referential integrity and participation are both bidirectional, meaning that they must be addressed in both directions along a relationship.

answer

False

question

The Crow's Foot notation easily identifies multivalued attributes.

answer

False

question

A ____ relationship exists when an association is maintained within a single entity

answer

unary

question

The ____ constraint can be placed on a column to ensure that every row in the table has a value for that column

answer

NOT NULL

question

Data attributes contain calendar dates stored in a specific format known as the ___ date format

answer

Julian

question

The row's range of permissible values is known as its domain.

answer

False

question

A data dictionary is sometimes described as "the database designer's database" because it records the design decisions about tables and their structures.

answer

True

question

In the relational model, _____ are important because they are used to ensure that each row in a table is uniquely identifiable.

answer

keys

question

The one-to-many (1:M) relationship is easily implemented in the relational model by putting the foreign key of the "1" side in the table of the "many" side as a primary key.

answer

False

question

To be considered minimally relational, the DBMS must support the key relational operators _____, PROJECT, and JOIN.

answer

SELECT

question

_____ logic, used extensively in mathematics, provides a framework in which an assertion (statement of fact) can be verified as either true or false.

answer

Predicate

question

Each table in a relational database must have a primary key.

answer

True

question

Each table ____ represents an attribute

answer

column

question

____ returns only the attributes requested, in the order in which they are requested.

answer

PROJECT

question

_____, also known as RESTRICT, yields values for all rows found in a table that satisfy a given condition.

answer

SELECT

question

Character data can contain any character or symbol intended for mathematical manipulation.

answer

True

question

A(n) _____ join links tables by selecting only the rows with common values in their common attribute(s).

answer

natural

question

When two or more tables share the same number of columns, and when their corresponding columns share the same or compatible domains, they are said to be _____.

answer

union-compatible

question

The ____ relationship is the "relational model ideal."

answer

1:M

question

Depending on the sophistication of the application development software, nulls can create problems when functions such as COUNT, AVERAGE, and SUM are used

answer

True

question

A(n) _____ is an orderly arrangement used to logically access rows in a table.

answer

index

question

The practical significance of taking the logical view of a database is that it serves as a reminder of the simple file concept of data storage.

answer

True

question

The idea of determination is unique to the database environment.

answer

False

question

The entity relationship model (ERM) is dependent on the database type.

answer

False

question

A composite identifier is a primary key composed of more than one attribute.

answer

True

question

In implementation terms, an entity is existence-dependent if it has a mandatory primary key.

answer

False

question

If Tiny College has some departments that are classified as "research only" and do not offer courses, the COURSE entity of the college database would be _____ the DEPARTMENT entity.

answer

optional to

question

To simplify the conceptual design, most higher-order relationships are decomposed into appropriate equivalent _____ relationships whenever possible.

answer

binary

question

The existence of a(n) ___entity indicates that its minimum cardinality is zero.

answer

optional

question

In the entity relationship model, a table row corresponds to an entity instance.

answer

True

question

a ____ relationship exists when three entities are associate.

answer

ternary

question

A weak entity has a primary key that is partially or totally derived from the parent entity in the relationship.

answer

true

question

If an employee within an EMPLOYEE entity has a relationship with itself, that relationship is known as a _____ relationship.

answer

recursive

question

In Chen notation, there is no way to represent cardinality

answer

False

question

In the original Chen notation, each attribute is represented by an oval with the attribute name connected to an entity rectangle with a line.

answer

True

question

The first step in building an entity-relationship diagram (ERD) is ____.

answer

creating a detailed narrative of the organization's description of operations

question

An entity in the entity relationship model corresponds to a table in the relational environment.

answer

True

question

The process of database design is a sequential process

answer

False

question

The Crow's Foot notation is less implementation-oriented than the Chen notation.

answer

False

question

Software vendors have adopted the Chen representation because of its compact representation.

answer

False

question

A derived attribute is indicated in the Chen notation by a _____ that connects the attribute and an entity.

answer

dashed line

question

The conceptual model can handle ____ relationships and multivalued attributes.

answer

M:N

question

In organizations that generate large number of transactions, _____ are often a top priority in database design.

answer

high processing speeds

question

If an entity can exist apart from all of its related entities, then it is existence-independent, and it is referred to as a(n) _____ entity.

answer

strong

question

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

answer

True

question

Entity supertypes and subtypes are organized in a specialization hierarchy.

answer

True

question

_____ is the bottom-up process of identifying a higher-level, more generic entity supertype from lower-level entity subtypes.

answer

Generalization

question

Which of the following is a specialization hierarchy disjoint constraint scenario in case of partial completeness?

answer

Subtype discriminator can be null

question

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

answer

False

question

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

answer

False

question

Overlapping subtypes are subtypes that contain ____ subsets of the supertype entity set.

answer

nonunique

question

In the context of total completeness, in a(n) _____, every supertype occurrence is a member of at least one subtype.

answer

overlapping constraint

question

An entity cluster is a "virtual" entity type used to represent multiple entities and relationships in the ERD.

answer

True

question

When selecting a foreign key placement for a 1:1 relationship, place the PK of the entity on the mandatory side in the entity on the optional side as a FK, and make the FK mandatory when _____.

answer

one side is mandatory and the other side is optional

question

In the context of total completeness, in a(n) _____, every supertype occurrence is a member of only one subtype.

answer

disjoint constraint

question

An entity cluster is formed by combining multiple interrelated entities into _____.

answer

a single abstract entity object

question

The function of the primary key is to describe an entity

answer

False

question

A _____ occurs when there is 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.

answer

fan trap

question

The preferred placement for a foreign key when working with a 1:1 relationship is to _____.

answer

place the foreign key in one of the entities

question

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

answer

inheritance

question

To model time-variant data, one must create a new entity in an M:N relationship with the original entity.

answer

False

question

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

answer

equality

question

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

answer

1:1

question

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

answer

natural

question

Entity subtypes do not inherit the relationships in which the supertype entity participates.

answer

False

question

Atomic attributes are attributes that can be further subdivided.

answer

False

question

Normalization represents a micro view of the ___ within the ERD.

answer

entities

question

In a(n) ____ diagram, the arrows above the attributes indicate all desirable dependencies.

answer

dependency

question

Of the following normal forms, ____ is mostly of theoretical interest.

answer

DKNF

question

In order to meet performance requirements, portions of the database design may need to be occasionally denormalized.

answer

True

question

Data redundancy produces ____.

answer

data integrity problems

question

A dependency based on only a part of a composite primary key is known as a partial dependency.

answer

True

question

In a _____ situation, one key determines multiple values of two other attributes and those attributes are independent of each other.

answer

multivalued dependency

question

Since a partial dependency can exist only if a table's primary key is composed of several attributes, if a table in 1NF has a single-attribute primary key, then the table is automatically in 2NF.

answer

True

question

Data stored at their highest level of granularity are said to be atomic data.

answer

False

question

Most designers consider the BCNF as a special case of the ____.

answer

3NF

question

For most business transactional databases, we should normalize relations into ____.

answer

3NF

question

A table is in 4NF if it is in 3NF, and ____.

answer

it has no multivalued dependencies

question

The most likely data type for a surrogate key is ____.

answer

numeric

question

In a real-world environment, we must strike a balance between design integrity and _____.

answer

flexibility

question

A table where every determinant is a candidate key is said to be in _____.

answer

BCNF

question

Attributes should clearly define participation, connectivity, and document cardinality.

answer

False

question

Data redundancy produces data anomalies.

answer

True

question

The conflicts between design efficiency, information requirements, and performance are often resolved through _____.

answer

compromises that include denormalization

question

When designing a database, you should ____.

answer

make sure entities are in normal form before table structures are created

question

Improving ____ leads to more flexible queries.

answer

atomicity

Ch 3-6 Quiz Answers – Flashcards

Unlock all answers in this set

Haven't found what you were looking for?

Search for samples, answers to your questions and flashcards