Deck 3: The Relational Model and Normalization

Question 1

A characteristic of a relation is that the rows of a relation may hold identical values.

Answer 1

False

Question 2

In functional dependencies,the attribute whose value is known or given is referred to as the determinant.

Answer 2

True

Question 3

In relational terms as defined by E.F.Codd,a row is called a tuple.

Answer 3

True

Question 4

Given the functional dependency (A,B)→ C,then it is true that A → C and B → C.

Question 5

Functional dependencies can involve groups of attributes.

Question 6

A functional dependency is a relationship between attributes such that if we know the value of one attribute,we can determine the value of the other attribute.

Question 7

Attribute Y is functionally dependent on attribute X if the value of attribute X determines the value of Y.

Question 8

In the functional dependency shown as A → B,B is the determinant.

Question 9

The columns of a relation are sometimes called tuples.

Question 10

If by knowing the value of A we can find the value of B,then we would say that B is functionally dependent on A.

Question 11

A relation is a three-dimensional table.

Question 12

Given the functional dependency A → (B,C),then it is true that A → B and A → C.

Question 13

In relational terms as defined by E.F.Codd,a column is called an attribute.

Question 14

A characteristic of a relation is that the cells of the relation hold a single value.

Question 15

Given the functional dependency (A,B)→ C,the attributes (A,B)are referred to as a composite determinant.

Question 16

A relation is a table composed of columns and rows.

Question 17

A tuple is a group of one or more columns that uniquely identifies a row.

Question 18

The functional dependency noted as A → B means that the value of A can be determined from the value of B.

Question 19

All relations are tables,but not all tables are relations.

Question 20

Given the functional dependency A → B,then it is necessarily true that B → A.

Question 21

A relation can have only one candidate key.

Question 22

A candidate key is one of a group of keys that may serve as the primary key in a relation.

Question 23

A primary key is a candidate key that has been selected to uniquely identify rows in a relation.

Question 24

A determinant of a functional dependency may or may not be unique in a relation.

Question 25

A combination key is a group of attributes that uniquely identifies a row.

Question 26

A constraint that requires an instance of an entity to exist in one relation before it can be referenced in another relation is called an insertion anomaly.

Question 27

A surrogate key is an artificial column that is added to a relation to be its primary key.

Question 28

Undesirable consequences of changing the data in a relation are called "modification anomalies."

Question 29

A deletion anomaly exists when deleting data about one entity results in the loss of data about another entity.

Question 30

Relations are classified into "normal forms" based on the types of modification anomalies that they are vulnerable to.

Question 31

A key can be composed of a group of attributes taken together.

Question 32

Surrogate keys are normally not shown on forms or reports.

Question 33

A foreign key is one or more columns in one relation that also is the primary key in another table.

Question 34

If a table meets the minimum definition of a relation,it has an effective or appropriate structure.

Question 35

A referential integrity constraint is used to make sure the values of a foreign key match a valid value of a primary key.

Question 36

A referential integrity constraint limits the values of a foreign key.

Question 37

A row can be uniquely identified by a key.

Question 38

A key is a combination of one or more columns that is used to identify particular rows in a relation.

Question 39

It is possible to have a relation that does not have a key.

Question 40

Surrogate keys usually slow performance.

Question 41

Any table that meets the definition of a relation is in 2NF.

Question 42

A defining requirement for Boyce-Codd Normal Form (BCNF)is that every candidate key must be a determinant.

Question 43

A relation ________.

A)has rows containing data about an entity
B)has columns containing data about attributes of the entity
C)has cells that hold only a single value
D)has no two identical rows
E)All of the above.

Question 44

In a relation ________.

A)entities in a column vary as to kind
B)the order of the columns is important
C)the order of the rows is unimportant
D)more than one column can use the same name
E)All of the above.

Question 45

Candidate keys are called interlocking candidate keys when they share one or more attributes.

Question 46

An attribute is considered to be a non-key attribute when it is a non-prime attribute,which means that the attribute is not contained in any candidate key.

Question 47

Every time we break up a relation during the normalization process,we may have to create a referential integrity constraint.

Question 48

Domain/key normal form requires that every constraint be a logical consequence of the definition of domains and keys.

Question 49

A relation that is in domain/key normal form is assured to be free from all anomalies.

Question 50

A relation is in 4NF if it is in BCNF and it has no multivalued dependencies.

Question 51

The multivalued dependency noted as A → → B,means that the value of A determines a set of values of B.

Question 52

A relation is in 4NF when multivalued dependencies are isolated in their own relation.

Question 53

A multivalued dependency exists when a determinant is matched to a set of values.

Question 54

When designing or normalizing relations,each relation should have only one theme.

Question 55

A relation is in Boyce-Codd Normal Form (BCNF)if and only if it is in 3NF and every determinant is a candidate key.

Question 56

A relation is in 2NF if and only if it is in 1NF and all non-key attributes are determined by the entire primary key.

Question 57

Any table that meets the definition of a relation is said to be in first normal form (1NF).

Question 58

A relation is in 3NF if and only if it is in 2NF and there are no non-key attributes determined by another non-key attribute.

Question 59

The essence of normalization is taking a relation that is not in BCNF and breaking it into multiple relations such that each one is in BCNF.

Question 60

The condition that a non-key attribute determines another non-key attribute is know as transitive dependency.

Question 61

A relation is also known as a(n)________.

A)table
B)tuple
C)relationship
D)attribute
E)field

Question 62

An attribute is also known as a ________.

A)table
B)relation
C)row
D)field
E)file

Question 63

If the removal of facts about one entity results in the unintentional loss of data about another entity,this is referred to as a(n)________.

A)normalization anomaly
B)insertion anomaly
C)update anomaly
D)deletion anomaly
E)removal anomaly

Question 64

When designing a database,one of the candidate keys in a relation is selected as the ________.

A)composite key
B)primary key
C)foreign key
D)surrogate key
E)dependency

Question 65

A combination of one or more columns used to identify particular rows in a relation is a ________.

A)record
B)field
C)key
D)tuple
E)dependency

Question 66

Which of the following is true about the functional dependency A → (X,Y)?

A)X is functionally dependent on A.
B)A determines Y.
C)A is a determinant.
D)X and Y are functionally dependent on A.
E)All of the above.

Question 67

Referential integrity constraints are used to limit the possible values of a ________.

A)composite key
B)candidate key
C)foreign key
D)surrogate key
E)dependency

Question 68

A key consisting of one or more columns that is a primary key in another relation is a ________.

A)composite key
B)candidate key
C)foreign key
D)surrogate key
E)dependency

Question 69

Normalization is a process used to deal with which of the following modification anomalies?

A)Insertion anomaly
B)Update anomaly
C)Deletion anomaly
D)A and B
E)A,B and C

Question 70

A ________ is used to limit the possible values of a foreign key.

A)composite key
B)surrogate key
C)functional dependency
D)referential integrity constraint
E)normal form

Question 71

A determinant that determines all the other columns in a relation is a ________.

A)record
B)field
C)foreign key
D)candidate key
E)surrogate key

Question 72

The only reason(s)for having relations is to ________.

A)store instances of functional dependencies
B)store equation components
C)store equation results
D)B and C
E)A,B and C

Question 73

Saying that two entities are functionally dependent means that ________.

A)the entities are always connected by a mathematical equation
B)for one of the entities,if we are given the value of that entity,we can determine the value of one other entity
C)for both of the entities,if we are given the value of that entity,we can determine the value of one other entity
D)the functional dependency will have to be removed through normalization
E)All of the above.

Question 74

Which of the following is true about the functional dependency (A,B)→ (C,D)?

A)A is the determinant of C.
B)A and B together are determined by C and D together.
C)A and B together determine D.
D)C and D together determine A.
E)A determines B.

Question 75

Given the functional dependency (A,B)→ C,then ________.

A)A → B
B)A → C
C)B → A
D)B → C
E)None of the above is correct.

Question 76

A combination of two or more columns used to identify particular rows in a relation is a ________.

A)record
B)field
C)composite key
D)foreign key
E)surrogate key

Question 77

An artificial column added to a relation to serve as the primary key is a ________.

A)composite key
B)candidate key
C)foreign key
D)surrogate key
E)dependency

Question 78

Given the functional dependency (A,B)→ C,(A,B)is a(n)________.

A)independent variable
B)dependent variable
C)determinant
D)composite determinant
E)C and D

Question 79

Given the functional dependency A → (B,C),A is a(n)________.

A)independent variable
B)dependent variable
C)determinant
D)composite determinant
E)C and D

Question 80

A tuple is also known as a ________.

A)table
B)relation
C)row
D)field
E)file