DD Test I

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

(1,1)

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.

(min, max)

The hierarchical data model was developed in the ______.

1970s.

The object-oriented data model was developed in the______.

1980s

The ________ relationship is the "relational model ideal."

1:M

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

A single abstract entity object

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

Candidate

________ expresses the minimum and maximum number of entity occurrences associated with one occurrence of the related entity.

Cardinality

Which of the following types of HDFS nodes acts as the interface between the user application and the HDFS?

Client node

Each table ______ represents an attribute.

Column

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

Composite

The entity relationship diagram (ERD) represents the database as viewed by the end user.

Conceptual

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

Data dictionary

_________ exists when different versions of the same data appear in different places.

Data inconsistency

________ server as the intermediary between the user and the database.

Database Management System DBMS

The term __________ refers to an organization of components that define and regulate the collection, storage, management and use of data within a database environment.

Database system

The extended entity relationship model (EERM) is sometimes referred to as the _______.

Enhanced entity relationship model

An ___________ database is used by an organization and supports many users across many departments.

Enterprise

A relationship is an association between ____________.

Entities

A(n) ______ is anything about which data are to be collected and stored.

Entity

The _______ model uses the term connectivity to label the relationship types.

Entity relationship.

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

False

An implementation-ready data model needn't necessarily contain enforceable rules to guarantee the integrity of the data.

False

Composite attributes make it easier to facilitate detailed queries.

False

Data and information are essentially the same thing.

False

Data anomaly is defined as the condition in which all of the data in the database are consistent with real-world events and conditions.

False

Database designers determine the data and information that yield the required understanding of the entire business.

False

Disjoint subtypes are subtypes that contain nonunique subsets of the supertype entity set.

False

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

False

Field refers to a collection of related records.

False

In Chen notation, there is no way to represent cardinality.

False

In an SQL-based relational database, each table is dependent on every other table.

False

Only a single attribute, not multiple attributes can define functional depedence.

False

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

False

Relationships between entities always operate in one direction.

False

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

False

Structural dependence exists when it is possible to make changes in the file structure without affecting the application program's ability to access the data.

False

The Crow's Foot notation easily identifies multivalued attributes.

False

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

False

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

False

The idea of determination is unique to the database environment.

False

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.

False

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

False

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

False

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

False

Business rules apply to business and government groups, but not to other types of organizations such as religious groups or research laboratories.

False.

Data attributes contain calender dates stored in a special format known as the _______ date format.

Julian

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

Keys

The conceptual model can handle ___________ relationships and multivalued attributes.

M:N

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

M:N

According to Codd's ________ rule of relational databases, if the system supports low-level access to the data, users must not be allowed to bypass the integrity rules of the database.

Nonsubversion

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

Nonunique

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

Outer joins

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

Primary

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

SELECT

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

SELECT

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

Should have the minimum number of attributes possible.

The _______ depicts the arrangement of higher-level entity supertypes (parent entities) and lower-level entity subtypes (child entities).

Specialization hierarchy.

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

Subtype discriminator can be null.

A ______ is any key that uniquely identifies each row.

Superkey

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

Supertype has optional subtypes.

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

Symbols

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

System catalog

Which of the following is true of business rules?

They can server as a communication tool between the users and designers.

What is true of spreadsheet applications?

They enhance the user's ability to understand the data.

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

True

A data warehouse can store data derived from many sources.

True

A design trap occurs when a relationship is improperly or incompletely identified and is therefore represented in a way that is not consistent with the real world.

True

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.

True

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

True

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

True

An entity supertype can have disjoint or overlapping entity subtypes.

True

As rare as 1:1 relationships should be, certain conditions absolutely require their use.

True

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

True

Each row in the relation table is known as entity instance or entity occurrence in the ER model.

True

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

True

Entity supertypes and subtypes are organized in a specialization hierarchy.

True

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

True

One disadvantage of a database system over previous data management approaches is increased costs.

True

One disadvantage of the DBMS is that it increases the risk of data security breaches.

True

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

True

To implement a small database, a database designer must know the "1" and the "M" sides of each relationship and whether the relationships are mandatory or optional.

True

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

True

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.

Unique values

_______ data exist in a format that does not lend itself to processing that yields information.

Unstructured

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

binary

Another name for a composite entity is a(n) ________ entity.

bridge

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

dashed line

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

disjoint constraint

A noun in a business rule translates to a(n) _________ in the data model.

entity

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

equality

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

existence

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

high processing speeds

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

index

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

inheritance

According to Codd's _______ rule of relational databases, 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).

logical data independence

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

natural

Ideally, an entity identifier is composed of _______ attributes(s)

one

Within a specialization hierarchy, every subtype can have ______ supertype(s) to which it is directly related.

only one

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.

security-compliant