Deck 5: Understanding Entity Relations

Question 1

One of the attributes an entity type should always have is a primary key.

Answer 1

True

Question 2

Generalization hierarchies must have both disjointness and completeness constraints.

Answer 2

False
Explanation: They can lack one of both constraints.

Question 3

A 1-M relationship cannot have any attributes.

Answer 3

False
Explanation: Although it is not common, a 1-M relationship can have any attributes.

Question 4

When a weak entity lacks at least one identifying relationship,this problem can be corrected by either adding an identifying relationship or converting the weak entity into a regular entity.

Question 5

In an identifying relationship,both of the participating entity types must be weak.

Question 6

In a generalization hierarchy,since each subtype entity is a supertype entity,the relationship between the two is known as ISA.

Question 7

An ERD diagram and a relational database diagram are similar in that both allow relationships to have attributes.

Question 8

By way of comparison to natural language,relationships can be said to correspond to nouns,and entity types can be said to correspond to verbs or prepositional phrases.

Question 9

Unary relationships are sometimes called reflexive relationships because they are like a reflection in a mirror.

Question 10

In Crow's Foot notation,the maximum cardinality symbol is placed toward the relationship name,and the minimum cardinality symbol is placed toward the entity type.

Question 11

In an ERD diagram,primary and foreign keys are shown for each entity type.

Question 12

Identification dependency is a type of existence dependency.

Question 13

A relationship that connects two entity types is called a unary relationship.

Question 14

In certain cases,adding an additional attribute to and entity can be used in place of a self-referencing relationship.

Question 15

In a multiple level generalization hierarchy,the attributes of the supertype are inherited by all levels of the subtypes,either directly or indirectly.

Question 16

In Crow's Foot and most other notations,entity types are denoted by a triangle.

Question 17

Named relationships are found in both relational database diagrams and ERD notation.

Question 18

In an ERD that conforms to the consistency rules of diagramming,all relationships must connect two entity types,and relationships must not be connected to other relationships.

Question 19

If an attribute is associated with only one entity type,the attribute should be shown as part of a relationship that the entity type participates in.

Question 20

Adherence to the completeness and consistency rules of ERD diagramming will ensure that an ERD provides an adequate data representation and that all user requirements are represented.

Question 21

The following is a weak entity:

A) Book
B) Author
C) Volume
D) Country

Question 22

The following qualifies as existence dependent:

A) Author on Written-by
B) Author on Born-in
C) Book on Written-by
D) All of the above

Question 23

The following qualifies as optional:

A) Written-by to Author
B) Born-in to Author
C) Born-in to Country
D) All of the above

Question 24

Written-by is:

A) An M-way relationship
B) A M-N relationship
C) An entity
D) A 1-M relationship

Question 25

Born-in is:

A) An M-way relationship
B) A M-N relationship
C) An entity
D) A 1-M relationship

Question 26

If there was no requirement to include the areas of countries in the database,cname (country name)could be made:

A) An attribute of Author
B) The primary key of Author
C) A relationship involving Author
D) An attribute of Written-by

Question 27

In an ERD,each generalization hierarchy must participate in at least one relationship with an entity type not in the generalization hierarchy.

Question 28

If we want to indicate that the authors of a book have conceived it when visiting another author in some country,we would use a relationship that is:

A) M-N
B) 1-1
C) 1-M
D) ternary

Question 29

Any author in the database has written:

A) One book only
B) One or several books
C) More than one book
D) Zero, one, or several books

Question 30

Any author in the database:

A) Has written a book as the sole author
B) May be without a book in the database
C) Has written a book with another author
D) Has written at least one book, with or without another author

Question 31

The following is not a primary key:

A) Volume#
B) Title
C) Aname
D) Cname

Question 32

No two books in the database:

A) May have the same publisher
B) May have been written by the same author
C) May have the same title
D) All of the above

Question 33

Any book in the database has been written by:

A) One author only
B) One or several authors
C) More than one author
D) Zero, one, or several authors

Question 34

The primary key of Volume is:

A) Volume#
B) #-of-pages
C) The combination Volume# and Title
D) The combination Volume# and #-of-pages

Question 35

If we want to indicate that the authors of a book have conceived it when visiting another author in some country,we would use a relationship that would connect:

A) Book to Country
B) Book to Country and Author
C) Author to Author
D) Author to Country

Question 36

Volume on Consists-of is:

A) Existence dependent
B) Identification dependent
C) All of the above
D) None of the above

Question 37

If we want to add the relationship "First-published-in" between Book and Country,it would be:

A) M-N
B) 1-1
C) 1-M
D) ternary

Question 38

If we want to add the relationship "Published-in" between Book and Country,it would be:

A) M-N
B) 1-1
C) 1-M
D) M-way

Question 39

If we want to add the relationship "Published-in" between Book and Country and indicate the number of copies of the book sold (copies-sold)in the countries,copies-sold would be:

A) An attribute of Book
B) An attribute of Country
C) An attribute of Published-in
D) A weak entity identified by Book

Question 40

Author-rank-in-book is:

A) An attribute
B) An entity
C) A relationship
D) A primary key

Question 41

Any md practices in:

A) One or several departments
B) Exactly one department
C) Zero or more departments
D) Two or more departments

Question 42

In an ERD,the minimum and maximum __________________ are specified for both directions of a relationship.

Question 43

If we want to indicate that the authors of a book have conceived it when visiting another author in some country,the symbol used in the Crow's Foot notation would be:

A) A relationship connecting Book, Country, and Author
B) An associative entity type "conceived" connecting to Book, Country, and Author each by binary relationships
C) Three binary relationships connecting pairwise Book, Country, and Author
D) Two binary relationships connecting Book and Country, and Book and Author

Question 44

In an ERD,a property of an entity type or relationship is known as a(n)___________________.

Question 45

When an entity cannot exist unless another related entity exists,this is known as __________________.

Question 46

Which of the following entities does not inherit the primary key SS#?

A) Administrator
B) Department
C) RN
D) Md

Question 47

In Crow's Foot notation,the Crow's Foot (two angled lines and one straight line)means a cardinality of ______________.

Question 48

A(n)______________ relationship is indicated by a minimum cardinality of one or more.

Question 49

In an ERD,a named association among entity types is known as a(n)_____________________.

Question 50

What statement is not true regarding inheritance in a generalization hierarchy:

A) The attributes of the supertype apply to all of the subtypes
B) Every subtype entity is also a supertype entity
C) Attributes inherited from a supertype are shown in an ERD
D) All of the above

Question 51

Which of the following statements is true?

A) An md may be an administrator
B) An RN may be an administrator
C) An md may not be an administrator
D) An md may be an RN

Question 52

Which of the following statements is true?

A) A staff may exist that is neither an RN, nor an administrator, nor an md
B) Every staff is either an RN, an administrator, or an md
C) A staff may exist that is an RN and an administrator
D) A staff may exist that is an administrator and an md

Question 53

In Crow's Foot notation,a line perpendicular to the relationship line means a cardinality of ______________.

Question 54

In Crow's Foot notation,a circle means a cardinality of ______________.

Question 55

If we want to indicate that the authors of a book have conceived it when visiting another author in some country,the usual symbol used in the Chen ERD notation would be:

A) A relationship connecting Book, Country, and Author
B) An associative entity type connecting to Book and Country
C) Three binary relationships connecting pairwise Book, Country, and Author
D) Two binary relationships connecting Book and Country, and Book and Author

Question 56

A collection of persons,places,events or things of interest in an application is called a(n)___________________.

Question 57

The number of administrators is:

A) Always the same as the number of departments
B) Always smaller than the number of departments
C) Smaller than or equal to the number of departments
D) Larger than or equal to the number of departments

Question 58

In reviewing an ERD for consistency,the property of uniqueness applies to:

A) Entity type names
B) Attribute names within entity types and relationships
C) Attribute names in a subtype
D) All of the above

Question 59

A(n)______________ relationship is indicated by a minimum cardinality of zero.

Question 60

In the ERD shown in 5-2,any RN works:

A) In one or several departments
B) In exactly one department
C) In zero or more departments
D) In two or more departments

Question 61

The relationship(s)that provides the components of a weak entity's primary key is known as a(n)___________________.

Question 62

A relationship with a maximum cardinality of one in one direction and a maximum cardinality of more than one in the other direction is a(n)_____________ relationship.

Question 63

When attribute(s)are associated with a combination of entity types instead of a single entity type,this relationship is usually (but not always)a(n)________________ relationship.

Question 64

An entity type that does not have its own primary key,but instead borrows part or all of its primary key from another entity type is known as a(n)___________________.

Question 65

___________________ occurs when an M-N relationship can be replaced by an associative entity type and two identifying 1-M relationships.

Question 66

A relationship that involves more than two entity types is called a(n)__________________ relationship.

Question 67

Since a room does not have a separate identity from the building it is physically located in,in terms of an ERD it can be said that there is a(n)___________________ between the room and the building.

Question 68

To depict a hierarchical chart of accounts in an ERD,you would probably have to use a(n)__________________ relationship.

Question 69

A(n)_____________________ relationship represents an association between members of the same set.

Question 70

With regards to a generalization hierarchy,the __________________ constraint means that subtypes do not have any entities in common.

Question 71

With regards to a generalization hierarchy,the __________________ constraint means that every entity of a supertype must be an entity in one of the subtypes.

Question 72

A relationship with a maximum cardinality of more than one in both directions is a(n)_____________ relationship.

Question 73

____________________ is a data modeling concept that supports the sharing of attributes between a supertype and a subtype.

Question 74

An M-way relationship between three entity types is known as a(n)____________ relationship.

Question 75

In a business situation where an employee can occupy only a single office and an office can only be occupied by one employee,this is an example of a(n)____________________ relationship.

Question 76

An entity type that depends on two or more entity types for its primary key is a(n)_______________ entity type.