It 214

A______ Is a field in a table which uniquely identifies each entity instance (row)na database.

A primary key

An entity is a:

An entity is a thing in the real or conceptual world.

Which of the following terms is used for the properties of entties?

Artributes are defined as properties of enccies

T/f: A unique tvalue) attribute is an attribute that have a unique (dfferent) value only for the entity instances that are aiready defined for the entity,

Aunique (value) attribute is an attribute that have a unique idifferent) value or no value at all for all entity instances (already defined or to be defined in the future)

An attribute that can be divided in simpler parts that have a different semantk meaning in the real world, is known as

Composite attribute

An attribute that can be divided in simpler parts that have a different semantic meaning in the real world, is known as:

Composite attribute attribute that can be divided in simpler parts that have a different semantic meaning in the real world is known as a composite attribute.

Given the following entity: EMPLOYEE(FIRST_NAME, MIDDLE_NAME, LAST_NAME, EMAIL, PHONE, DOB, ADDRESS), keeping contact information about employees in a company. Which is a possible primary key? (select the best answer)

Email: The only unique and required attribute will be EMAIL.

T/f:binary relationship exists when two entity instances are associated.

F: binary relationship exists when two entities are associated.

T/f: For the entity PERSON the attribute SSN is not an example of a unique values attribute.

False

T/f: For the entity PERSON the attribute address is an example ofa simple attribute.

False

T/f: In a database keeping the history of sold cars in a county, for the entity CAR the attribute price is not an example of a required attribute.

False : price is a required attribute

T/f: A relationship in ER model represents a property or attribute of an entiky.

False Relationships in ER model can be defined as an association among entities.

T/f: A "simple" primary key is composed of two or more attributes.

False: A "simple" primary key is composed of a single attribute.

T/f: "A STUDENT has a CLASS" is a recommended name for a relationship

False: A STUDENT takes a CLASS is a good name for a relationship

T/f: A datatuse is defined as any data stored and accessed on a computer system.

False: A database is an organized collection of data, it is generaly stored and accessed electranically from a computer system

T/f: A composite primary key must contain exactly two attributes.

False: A primary key containing two or more attributes is named composite primary key. Each attribute must be required (without null values). The tuples with the values for all the attributes must also be unique.

T/f: Arelationship degree indicates the number of entity instances associated with a relationship

False: A relationship degree indicates the number of entities or particigants associated with a relationship.

T/f: A unique (value) attribute is an attribute that have a unique (different) value only for the entity instances that are already defined for the entity.

False: A unique (value) attribute is an attribute that have a unique (different) value or no value at all for all entity instances (already defined or to be defined in the future).

T/f: Attributes can be defined as relations between entities.

False: Attributes can be defined as properties of entities.

T/f: A weak relationship is also known as an identifying relationship.

False: Aweak relationship is also known as a nonidentifying relationship.

T/f: Entities are named as verb phrases

False: Entities are named as singular nouns

T/f: The term "cardinality" for a relationsship expresses the number of entities associated by the relationship

False: Entity Cardinality in a relationship expresses the minimum and maximum number of entity instances occurrences associated with one entity instance occurrence of the related entity.

T/f: For the entity CAR the attribute cost is an example of a composite attribute.

False: For the entity CAR the attribute cost is an example of a simple attribute, because is a number and cannot be divided in subparts.

T/f: For the entity PERSON the attribute first_name is not an example of an optional attribute.

False: For the entity PERSON the attribute first_name is not an example of an optional attribute, because all persons must have a first name. By definition, an optional attribute is an attribute that may not have a value for some entity instances (already defined or to be defined in the future).

T/f: Knowledge resolves uncertainty and represents processed data.

False: Knowledge is the awareness and understanding of something (e.g. entity) based on the information acquired about it.

T/f: The gender of a person is an example of a multi-value attribute.

False: The gender of a person is an example of single-value attribute, because any person has a single gender.

T/f: The emails of a person are an example of single value attributes.

False: The list of emails of a person not an example of single-value attribute, because some persons may have several emails.

T/f: The phone numbers of a person is an example of single-value attribute.

False: The phone numbers of a person is not an example of single-value attribute, because some persons may have several phone numbers.

True/false: A single-value attribute has at least a value for any given entity instance.

False: The single-valued attribute has at most a single value for any given entity instance. It may not have any value for some entity Instances.

T/f: The title of a course is an example of a multi-value attribute.

False: The title of a course is an example of single-value attribute, because any course has a single title.

T/f: While naming entities if the name uses multiple words, separate them by semicolon.

False: While naming entities if the name uses multiple words, separate them by ___

t/f: A subtype discriminator is an attribute in the subtype entity that determines to which super type the subtype occurrence is related.

False: a subtype discriminator is the attribute in the super type entity that determine to which subtype the super type occurrence is related

T/f: A database organized in terms of objects, their properties and the relations between them is a relational database.

False: tuples

T/f: For the entity PERSON the attribute name is an example of a simple attribte.

Fla: For the entity PERSON the attribute attribute is an attribute that can be divided in simpler parts that have a different name is an exampie of a composite attribute, because it may be divided in first name, middle name, and last name that have semantic meaning in the real world.

Specification: A student is enrolled in many classes The above specification indicates a relationship having the type:

MANY to MANY because a class contain MANY students (common sensse assumption) and a student is enrolled in many classes Igiven

An attribute that may have two different values for two entity instances is named:

Multi-value atribute

A person may have a home phone number and a work phone number. Does this specification represents a relationship?

No , the specification "A person may have a home phone number and a work phone number." represents two attributes for a person, the home phone number and the work phone number, which are single-value attributes and they do not need a relationship for representation.

What is the notation for relational database management system?

RDBMS

An attribute that must have a value for all entity instances (already defined or to be defined in the future) is named _____

Required

An attribute that must have a value for all entity instances (already defined or to be defined in the future) is named:

Required

An attribute that cannnot be divided in simpler parts that have a different semantic meaning in the real world, is known as:

Simple attribute : an attribute that cannot be divided in simpler parts that have a different semantic meaning in the real world is known as a simple attribute. See topic DB-D1-

Which of the following attributes is defined as having at most a single value for any given entity instance?

Single-valued attributes

Given the following entity: EMPLOYEELFIRST NAME, MIDDLE NAME, LAST NAME, EMAIL, PHONE, DOB, ADORESSI keeping contact information about employees in a company Which is a possible primary key? (select the best answer)

The only unique and required attribute will be EMAIL

T/f : An optional attribute is an attribute that may not have a value for some entity instances (already defined or to be defined in the future).

True

T/f: A relationship in ER model represents an association among entities

True

T/f: A unary relationship exists when an association is maintained within a single entity.

True

T/f: A unique (value) attribute is an attribute that have a unique (different) value or no value at all for all entity instances (already defined or to be defined in the future)

True

T/f: An entity may be physical object such as a house or a car

True

T/f: Attributes are named with nouns or noun phrases.

True

T/f: Crow's foot notation depicts the strong (identifying) relationship with a solid" line between the entities

True

T/f: Data consists of raw facts, qualitative or quantitative characteristics of an entity.

True

T/f: Relationships names are verbs, linking two or more nouns

True

T/f: Strong relationship exists when the PK of the child entity contains the PK of the parent entity.

True

T/f: While naming entities if the name uses multiple words, separate them by____

True

True/ false: A relational database management system organizes the relations bettween several databases.

True

T/f: RDB is the notation for a relational database.

True : RDB is the notation for a relational database.

T/f: For the entity PERSON the attribute address is an example of a composite attribute

True: . For the entity PERSON the attribute address is an example of a composite attribute, because it may be divided in street, city, state, and zipcode that have a different semantic meaning. By definition, a composite attribute is an attribute that can be divided in simpler parts that have a different semantic meaning in the real world.

A multi-valued attribute has two or more values for some entity instances.

True: : A multi-valued attribute has two or more values for some entity instances.

T/f: For the entity CITY the attribute name is an example of a simple attribute.

True: For the entity CITY the attribute name is an example of a simple attribute, because is a unstructured text and cannot be divided in subparts. By definition, a simple attribute is an attribute that cannot be divided in simpler parts that have a different semantic meaning in the real world.

T/f: The relational model represents data in tuples grouped in relations.

True: The relational model represents data in tuples grouped in relations. A tuple contains the values for related attributes (l.e. columns) from a predefined data type (l.e, domain). When the relation is shown as a table, the tuples are the rows and attributes the columns. In design the relation correspond to an entity and the tuples to entity instances. It was introduced by Edgar F. Codd in 1969.

T/f: For the entity PERSON the attribute fullname is an example of a duplicated values attribute.

True: There are two persons that have the same full name, therefore fullname is duplicated value attribute.

True / false : Entities in ER model must be named using a consistent case notation.

True: Your answer is correct: Entities in ER model must be named using a consistent case notation, i.e. either all in capitals, or all capitalized, or all in lower cases.

The domain (set of values) of aln) _____ may represent an entity itself (eg, an address of a person, a city in which a person is living, the phone number of a person).

attribute

A ___relationship exists when two entities are associated

binary

an database is an organized ____ of data

collection

A primary key containing two or more attributes is named _____primary key.

composite

An _____attribute is an attribute that can be divided in simpler parts that have different semantic meaning in the real world.

composite

A_______is an organized collection of data.

database : database is an organized collection of data. It is generally stored and accessed electronically from a computer system.

A relationship _____ indicates the number of entities or participants associated with a relationship.

degree : A relationship degree indicates the number of entities or participants associated with a relationship.

an ___ has a discount existence as an individual unit

entity

the domain (set of values) of an attribute may represent an ______ itself.

entity

t/f: a relationship in er model represent a general real or abstract concept or entity

false

t/f: given a multi-value attribute with two value for which we need to process independently the values, but without performing global processing on all the values , it is recommended to consider a new dependent entity to represent the values.

false

t/f:given an entity with a set of related attribute describing on of it characteristics having a lot of duplicated tuples. for instance , for cars at a dealer it is stored the interior and exterior color . in this situation it is recommended to consider a new entity describing these attributes

false

t/f:attributes can be defined as relations between entities

false: attributes can be defined as properties of entities.

___ is a field (or collection of fields) in one table that uniquely identifies a row of another table or the same table.

foreign key

an entity ____ is described by the values of its attributes

instance

an entity is a :

model of relation in data

An) ______ attribute is an attribute that has two or more value for some entity instances

multi-valued

an album has a name does this specification represent a relationship ?

no

An attribute that may not have a value for some entity instances (already defined or to be defined in the future) is named:

optional You are correct. An optional attribute is an attribute that may not have a value for some entity instances (already defined or to be defined in the future). See topic DB-D1-43 Required and Optional Attributes.

the ______ completeness means that not every super type occurrence is a member of a subtype

partial

A _____ is a field in a table which uniquely identifies each entity instance (row)na database.

primary key

An _______attribute is an attribute that cannot be divided in simpler parts that have a different semantic meaning in the real worid.

simple

a____ discriminator is the attribute in the super type entity that determine to which subtype the supertype occurrence is related.

subtype

t/f :given a multi value attribute, with a variable number of values for which we need to process independently the values, it is recommended to consider a new dependent entity to represent the values .

true

t/f: a relationship in er model represent an association among entities

true

t/f: given a bridge with a candidate key with two attributes, it is usually not recommend to create a surrogate key for the bridge

true

t/f: given an entity that has candidate keys with 4 or more attribute it is usually recommended to create a surrogate key for the entity.

true

t/f: given an multi-valued attribute with a variable number of values for which we need to process independently the values, it is recommended to consider a new dependent entity to represent the values

true

t/ f: the following is an example of partial completeness for a hierarchy. given the super type employee with two subtype faculty and staff. an employee may be a faculty , a staff or have another role in the school.

true bc there are employees that are neither faculty nor staff.

The relational model represents data in ______ grouped in relations.

tuples