Deck 5: The Relational Database Model: Introduction

Question 1

The values of a candidate key of a relation ____.

A) cannot be unique
B) may be unique or non-unique
C) must be unique
D) must consist of a single attribute
E) None of the above.

Answer 1

C

Question 2

A candidate key of a relation that is not chosen to be the primary key ____.

A) is called a foreign key
B) is called an alternate key
C) is called a relationship key
D) does not have to have unique values
E) does not have to be wholly contained within the relation

Answer 2

B

Question 3

In a relation ____.

A) several rows can be identical
B) the columns must be arranged in a single, particular order
C) the rows must be arranged in a single, particular order
D) a single row/column position, called a cell, can have multiple values
E) None of the above.

Answer 3

E

Question 4

The attribute(s) that make up a foreign key in a relation of a database ____.

A) cannot appear in another relation of the database
B) may or may not appear in another relation of the database
C) must appear in another relation of the database
D) must have unique values in the relation in which it is a foreign key
E) must be part of the primary key in the relation in which it is a foreign key

Question 5

An attribute or combination of attributes that is a foreign key in one relation of a database must be ____ another relation in the database.

A) the primary key of
B) a secondary key of
C) an alternate key of
D) a non-unique attribute or combination of attributes of
E) None of the above.

Question 6

The primary key of the relation added to accomplish the many-to-many relationship ____.

A) must contain at least three attributes
B) must contain at least four attributes
C) is the primary key of one of the two relations involved in the many-to-many relationship
D) does not involve the primary keys of either of the two relations involved in the many-to-many relationship
E) is the combination of the primary keys of the two relations involved in the many-to-many relationship plus possible additional attributes

Question 7

All of the following are true about storing a one-to-one binary relationship in a relational database, except _____.

A) an additional relation must be added to the database
B) two additional relations must be added to the database
C) the primary key of one of the relations in placed in the other relation as a foreign key
D) the two relations involved in the one-to-one relationship can be combined into one relation
E) a particular value of the primary key of one relation is associated with exactly one value of the primary key of the other relation (or possibly with none)

Question 8

The values of the primary key of a relation ____.

A) cannot be unique
B) may be unique or non-unique
C) must be unique
D) must consist of a single attribute
E) None of the above.

Question 9

A foreign key ____.

A) must have the same column name(s) as the primary key from which it is derived
B) must not have the same column name(s) as the primary key from which it is derived
C) must have the same domain of values as the primary key from which it is derived
D) must not have the same domain of values as the primary key from which it is derived
E) must have a domain of values that is different from any other in the database

Question 10

The relational data model was first described in a paper by Dr. E. F. Codd in ____.

A) 1965
B) 1970
C) 1975
D) 1980
E) 1985

Question 11

In relational database, the basic data structure that appears to be similar to a file is called a ____.

A) relation
B) attribute
C) record
D) column
E) row

Question 12

An attribute(s) that acts as a foreign key in a relation ____.

A) must be the entire primary key of that relation
B) cannot be part of the primary key of that relation
C) may be part of the primary key of that relation
D) must also be a foreign key in another relation of the database
E) None of the above.

Question 13

Storing a binary many-to-many relationship in a relational database ____.

A) requires the insertion of a foreign key in one of the two relations representing the entities in the many-to-many relationship
B) requires the insertion of foreign keys in both of the relations representing the entities in the many-to-many relationship
C) does not require the addition of any additional relations
D) requires the addition of one additional relation
E) requires the addition of two additional relations

Question 14

Doctors and patients are in a binary one-to-many relationship as:
Doctor Patient To accomplish this in a relational database _____.

A) The primary key of the DOCTOR relation is placed as a foreign key in the PATIENT relation.
B) The primary key of the PATIENT relation is placed as a foreign key in the DOCTOR relation.
C) Either of choice a or b will work.
D) Neither of choice a or b will work.
E) Nothing extra has to be done to accomplish this in a relational database.

Question 15

An attribute(s) that functions as the primary key of relation A and as a foreign key in relation B of a relational database ____.

A) must have unique values in both relations
B) must have unique values in relation A
C) must have unique values in relation B
D) must not have unique values in either relation
E) must have unique values in one relation if it has unique values in the other

Question 16

Which of the following relational algebra commands or combination of commands is capable of retrieving one or more rows of a relation?

A) Select.
B) Project.
C) Join.
D) Select and Project.
E) Select, Project, and Join.

Question 17

Relational database management first became commercially viable in ____.

A) the late 1960s
B) the early 1970s
C) the late 1970s
D) the early 1980s
E) the late 1980s

Question 18

Which of the following relational algebra commands or combination of commands is capable of retrieving one or more columns of a relation?

A) Select.
B) Project.
C) Join.
D) Select and Project.
E) Select, Project, and Join.

Question 19

Consider relations X and Y, each representing one of two entities in a many-to-many binary relationship. Relation Z is the additional relation created to store the many-to-many relationship. Intersection data ____.

A) is stored in relation X or in relation Y, but not in both
B) must be stored in both relations X and Y
C) is stored in relation Z
D) is stored in all three relations X, Y, and Z
E) cannot be stored in any of relations X, Y, or Z

Question 20

All of the following events and factors in the early 1980s led to the introduction of relational database management, except ____.

A) the introduction of personal computers
B) the fact that hierarchical and network DBMSs were too complex for the PC environment
C) the need for a DBMS approach that would make the database design process simpler than that of the hierarchical and network approaches
D) improvements in relational DBMS performance
E) improvements in mainframe computer performance

Question 21

The columns of a relation can be arranged in any order without affecting the meaning of the data.

Question 22

A foreign key must have unique values in the relation in which it is a foreign key.

Question 23

A relational DBMS is capable of automating the cross-relation data extraction process in such a way that it appears that the data in the relation is integrated ____.

A) by a relational Select command
B) by a relational Project command
C) by the combination of relational Select and Project commands
D) while also remaining redundant
E) while also remaining nonredundant

Question 24

Performance issues delayed the introduction of relational database management systems as viable commercial products.

Question 25

Storing a many-to-many relationship in a relational database requires the creation of an additional relation.

Question 26

A relation's primary key field can have non-unique values.

Question 27

In a one-to-many binary relationship, the primary key from the "many side" of the relationship is inserted as a foreign key in the "one side" of the relationship.

Question 28

No two rows of a relation are identical.

Question 29

The result of a relational operation will always be a ____.

A) single cell value
B) row
C) column
D) relation
E) join

Question 30

The emergence of the personal computer influenced the emergence of relational database management.

Question 31

In relational database terminology, the terms row and relation are synonymous.

Question 32

A relation's primary key can include more than one attribute.

Question 33

Which of the following relational algebra commands or combination of commands is capable of retrieving a single cell value from the integrated result of two relations?

A) Select.
B) Project.
C) Join.
D) Select and Project.
E) Select, Project, and Join.

Question 34

Which of the following relational algebra commands or combination of commands is capable of retrieving a single cell value from a relation?

A) Select.
B) Project.
C) Join.
D) Select and Project.
E) Select, Project, and Join.

Question 35

Which of the following is true about the join fields used in a relational Join command?

A) They must have the same attribute names.
B) They must have the same domain of values.
C) They must both be foreign keys.
D) All of the above.
E) None of the above.

Question 36

Today, relational DBMSs have limited commercial use in niche areas only.

Question 37

Depending on the circumstances, it is possible that a foreign key is part of the primary key of the relation in which it is a foreign key.

Question 38

A candidate key that is not chosen as a relation's primary key is called an alternate key.

Question 39

A join in which one of the two identical join columns in the result is eliminated is called a(n) ____.

A) semijoin
B) equijoin
C) compound join
D) natural join
E) complex join

Question 40

In relational database terminology, the terms column and tuple are synonymous.

Question 41

Consider the following relational database for the Central Zoo. Central Zoo wants to maintain information about its animals, the enclosures in which they live, and its zookeepers and the services they perform for the animals. In addition, Central Zoo has a program by which people can be sponsor of animals. Central Zoo wants to track its sponsors, their dependents, and associated data.
Each animal has a unique animal number and each enclosure has a unique enclosure number. An animal can live in only one enclosure. An enclosure can have several animals in it or it can be currently empty. A zookeeper has a unique employee number. Every animal has been cared for by at least one and generally many zookeepers; each zookeeper has cared for at least one and generally many animals. Each time a zookeeper performs a specific, significant service for an animal the service type, date, and time are recorded. A zookeeper may perform a particular service on a particular animal more than once on a given day.
A sponsor, who has a unique sponsor number and a unique social security number, sponsors at least one and possibly several animals. An animal may have several sponsors or none. For each animal that a particular sponsor sponsors, the zoo wants to track the annual sponsorship contribution and renewal date. In addition, Central Zoo wants to keep track of each sponsor's dependents. A sponsor may have several dependents or none. A dependent is associated with exactly one sponsor.
ENCLOSURE Relation
ANIMAL Relation
ZOOKEEPER Relation
CARES FOR Relation
SPONSOR Relation
CONTRIBUTION Relation
DEPENDENT Relation
a. Identify the candidate keys of each relation.
b. Identify the primary key and any alternate keys of each relation.
c. How many foreign keys does each relation have?
d. Identify the foreign keys of each relation.
e. Indicate any instances in which a foreign key serves as part of the primary key of the relation in which it is a foreign key. Why does each of those relations require a multi-attribute primary key?
f. Identify the relations that support many-to-many relationships, the primary keys of those relations, and any intersection data.
g. Using the informal relational command language described in this chapter, write commands to:
i. Retrieve the record for animal number 58560.
ii. Retrieve the record for the tiger named Stripes.
iii. List all of the tigers born in India.
iv. List the name and animal number of every animal born in China that weighs less than 100 pounds .
v. List the name and number of every tiger.
vi. What is the country of birth of animal number 74371?
vii. What is the type and size of the enclosure used for animal number 74371?
viii. List the name and address of every sponsor of animal number 74371.

Question 42

The relational Project operator retrieves one or more rows from a relation.

Question 43

Intersection data describes the many-to-many relationship between two entities.

Question 44

The result of a relational algebra operation is a relation.

Question 45

In a relational Join operation, the join attributes must have the same domain of values.

Question 46

In an equijoin, one of the two identical join columns in the result is eliminated.

Question 47

The two primary keys representing the entities in the many-to-many relationship will always serve as the primary key in the additional relation representing the many-to-many relationship.

Question 48

Storing a many-to-many relationship in a relational database would require the creation of an additional relation even if there was no intersection data.

Question 49

The relational Select operator retrieves one or more columns from a relation.

Question 50

All of the data involved in a one-to-one binary relationship could be combined in one relation.

Question 51

Intersection data in a relational database is stored in one of the two relations representing the entities in the many-to-many relationship.

Question 52

Consider the following relational database for Grand Travel Airlines.
Grand Travel Airlines has to keep track of its flight and airplane history. A flight is uniquely identified by the combination of a flight number and a date. Every passenger who has flown on Grand Travel has a unique passenger number. For a particular passenger who has taken a particular flight, the company wants to keep track of the fare that she paid for it and the date that she made the reservation for it. Clearly, a passenger may have taken many flights (he must have taken at least one to be in the database) and every flight has had many passengers on it.
A pilot is identified by a unique pilot (or employee) number. A flight on a particular date has exactly one pilot. Each pilot has typically flown many flights but a pilot may be new to the company, is in training, and has not flown any flights, yet. Each airplane has a unique serial number. A flight on a particular date used one airplane. Each airplane has flown on many flights and dates, but a new airplane may not have been used at all, yet.
PILOT Relation
FLIGHT Relation
PASSENGER Relation
RESERVATION Relation
AIRPLANE Relation
a. Identify the candidate keys of each relation.
b. Identify the primary key and any alternate keys of each relation.
c. How many foreign keys does each relation have?
d. Identify the foreign keys of each relation.
e. Indicate any instances in which a foreign key serves as part of the primary key of the relation in which it is a foreign key. Why does each of those relations require a multi-attribute primary key?
f. Identify the relations that support many-to-many relationships, the primary keys of those relations, and any intersection data.
g. Using the informal relational command language described in this chapter, write commands to:
i. Retrieve the record for airplane number 36325.
ii. Retrieve the record for the pilot named Sarah Johnson who was born on 5/22/1959.
iii. List all of the airplanes manufactured by Boeing.
iv. List the airplane number and passenger capacity of every airplane manufactured by Boeing in 1997 .
v. List the airplane number, model, and manufacturer of every airplane.
vi. What company manufactured airplane number 53489?
vii. What was the name and date of birth of the pilot of flight number 182 on 10/30/2003?
viii. List the airplane number, model, and manufacturer of every airplane that was used on flight 118 in 2003.

Question 53

The relational Join operation accomplishes data integration in a relational database.

Question 54

The combination of a relational Select and a relational Project operation can return a single data value.

Question 55

In relational database management, data integration takes place at the time that a relational query is processed.

Question 56

In a relational Join operation, the join attributes must have the same attribute names.

Question 57

A one-to-one binary relationship can utilize a foreign key in much the same way as a one-to-many binary relationship.