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Cierto o falso de Capitulo 4

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#Megasparaalola
Angel Perez
Quiz by Angel Perez, updated more than 1 year ago
Angel Perez
Created by Angel Perez almost 8 years ago
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Resource summary

Question 1

Question
E-R models are expressed using a single standardized set of universally accepted symbols.
Answer
  • True
  • False

Question 2

Question
An entity is something in the users’ work environment that the users want to track.
Answer
  • True
  • False

Question 3

Question
Entities of a given type are grouped into entity classes.
Answer
  • True
  • False

Question 4

Question
An entity class is described by the structure of the entities in that class.
Answer
  • True
  • False

Question 5

Question
An entity instance of an entity class is the representation of a particular entity and is described by the values of the attributes of the entity.
Answer
  • True
  • False

Question 6

Question
In E-R modeling, entities within an entity class may have different attributes.
Answer
  • True
  • False

Question 7

Question
In E-R modeling, an attribute may be either composite or multi-valued, but it cannot be both.
Answer
  • True
  • False

Question 8

Question
An identifier of an entity instance must consist of one and only one attribute.
Answer
  • True
  • False

Question 9

Question
A “composite identifier” is defined as a composite attribute that is an identifier.
Answer
  • True
  • False

Question 10

Question
An identifier may be either unique or nonunique.
Answer
  • True
  • False

Question 11

Question
E-R modeling recognizes both relationship classes and relationship instances.
Answer
  • True
  • False

Question 12

Question
Relationships do not have attributes.
Answer
  • True
  • False

Question 13

Question
A single relationship class involves only one entity class.
Answer
  • True
  • False

Question 14

Question
A binary relationship is a relationship based on numerical entity instance identifiers.
Answer
  • True
  • False

Question 15

Question
The degree of a relationship is expressed as the relationship’s maximum cardinality.
Answer
  • True
  • False

Question 16

Question
A relationship’s minimum cardinality indicates whether or not an entity must be involved in the relationship.
Answer
  • True
  • False

Question 17

Question
Relationships among instances of a single entity class are called redundant relationships.
Answer
  • True
  • False

Question 18

Question
A weak entity is an entity that cannot exist in the database without (and is logically dependent upon) another type of entity also existing in the database.
Answer
  • True
  • False

Question 19

Question
ID-dependent entities are a common type of weak entity.
Answer
  • True
  • False

Question 20

Question
All weak entities must have a minimum cardinality of 1 on the entity on which it depends.
Answer
  • True
  • False

Question 21

Question
Multi-valued attributes are represented in E-R diagrams by creating a new weak entity to represent the multi-valued attribute and creating a 1:N relationship.
Answer
  • True
  • False

Question 22

Question
Subtype entities are used to produce a closer-fitting model when an entity has sets of optional attributes.
Answer
  • True
  • False

Question 23

Question
Entities with an IS-A relationship should have the same identifier.
Answer
  • True
  • False

Question 24

Question
Inheritance in a generalization hierarchy means that the supertype entity inherits all the attributes of the subtype entity.
Answer
  • True
  • False

Question 25

Question
It is not important to document business rules during data modeling since they will be enforced by the application programs.
Answer
  • True
  • False

Question 26

Question
UML is intended for modeling and designing object-oriented programs and applications.
Answer
  • True
  • False

Question 27

Question
For database design, UML-style E-R diagrams must be treated very differently from traditional E-R diagrams because of their object-oriented background.
Answer
  • True
  • False

Question 28

Question
Maximum cardinalities are represented in UML-style E-R diagrams with the same notation (1:1, 1:N, N:M) as in traditional E-R diagrams.
Answer
  • True
  • False

Question 29

Question
In UML-style E-R diagrams, a weak entity is shown by placing a filled-in diamond on the parent of the weak entity.
Answer
  • True
  • False

Question 30

Question
One weakness of UML-style E-R diagrams is that there is no means of distinguishing between a weak entity that is ID-dependent and a weak entity that is not ID-dependent.
Answer
  • True
  • False

Question 31

Question
UML-style E-R diagrams allow for the existence of class attributes, which are attributes that pertain to the collection of all entities within that class not to the individual entity instances
Answer
  • True
  • False

Question 32

Question
UML-style E-R diagrams allow for three different levels of visibility of attributes.
Answer
  • True
  • False

Question 33

Question
UML-style E-R diagrams introduce object-oriented notation that is of limited practical value in traditional, relational database design.
Answer
  • True
  • False

Question 34

Question
The goal of data models is to strive to produce the most accurate model of the real world as possible.
Answer
  • True
  • False
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