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ISE 224 > Chapter 3 > Flashcards

Chapter 3 Flashcards

0
Q

A relation is a three-dimensional table

A

False

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1
Q

All relations are tables, but not all tables are relations

A

True

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2
Q

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

A

True

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3
Q

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

A

False

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4
Q

A relation is a table composed of columns and rows

A

True

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5
Q

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

A

True

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6
Q

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

A

True

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7
Q

The columns of a relation are sometimes called tuples

A

False

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8
Q

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

A

False

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9
Q

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

A

True

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10
Q

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

A

True

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11
Q

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

A

True

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12
Q

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

A

True

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13
Q

The functional dependency noted as A -> B means that the value of A can be determined from the value or B

A

False

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14
Q

In the functional dependency shown as A -> B, B is the determinant

A

False

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15
Q

Functional dependencies can involve groups of attributes

A

True

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16
Q

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

A

True

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17
Q

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

A

True

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18
Q

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

A

False

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19
Q

Given the functional dependency A -> B, then it is necessarily true that B -> A

A

False

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20
Q

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

A

True

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21
Q

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

A

True

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22
Q

A row can be uniquely identified by a key

A

True

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23
Q

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

A

False

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24
Q

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

A

True

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25
Q

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

A

False

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26
Q

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

A

True

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27
Q

A relation can have only one candidate key

A

False

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28
Q

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

A

True

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29
Q

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

A

True

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30
Q

A surrogate key usually slow performance

A

False

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31
Q

Surrogate keys are normally not shown on forms or reports

A

True

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32
Q

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

A

True

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33
Q

A relation

A

Has rows containing data about an entity, has columns containing data about attributes of the entity, has cells that hold only a single value, has no two identical rows

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34
Q

In a relation

A

The order of the rows is unimportant

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35
Q

A relation is also known as a

36
Q

A tuple is also know as a

37
Q

An attribute is also known as a

38
Q

Saying that two entities are functionally dependent means that

A

For one of the entities, if we are given the value of that entity, we can determine the value of one other entity

39
Q

Given the functional dependency A -> (B, C), A is a

A

Determinant

40
Q

Given the functional dependency (A, B) -> C, (A, B) is a

A

Determinant and composite determinant

41
Q

Given the functional dependency (A, B) -> C, then

A

None of the above

42
Q

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

A

X is functionally dependent on A, A determines Y, A is a determinant, X and Y are functionally dependent on A

43
Q

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

A

A and B together determine D

44
Q

The only reason for having relations is to

A

Store instances of functional dependencies

45
Q

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

46
Q

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

A

Composite key

47
Q

A determinant determines all the other columns in a relation is a

A

Candidate key

48
Q

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

A

Primary key

49
Q

An artificial columnar added to a relation to serve as the primary keys is a

A

Surrogate key

50
Q

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

A

Foreign key

51
Q

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

52
Q

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

53
Q

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

54
Q

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

55
Q

Undesirable consequences of changing the data in a relation are called “modification anomalies”

56
Q

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

57
Q

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

58
Q

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

59
Q

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

60
Q

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.

61
Q

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.

62
Q

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

A

Foreign key

63
Q

A ______ is used to limit the possible values of a(n) foreign key

A

Referential integrity constraint

64
Q

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

A

Insertion anomaly, update anomaly, deletion anomaly

65
Q

If the removal of facts about one entity results in the unintentional loss of data about another entity, this is referred to as an

A

Deletion anomaly

66
Q

Suppose that you need to update one value if the column SalesCost in a relation. The way the relation is constructed, this value actually needs to be changed in three different rows. However, you can only change the value in two of the rows. You have just created a(n)

A

Update anomaly

67
Q

A table that meets the definition of a relation is in

A

First normal form

68
Q

A relation is in second normal form (2NF) if and only if it is in 1NF and

A

All non-key attributes are determined by the entire primary key

69
Q

A relation is in Boyce-Codd normal form (BCNF) if and only if it is in 3NF and

A

Every determinant is a candidate key

70
Q

If a table is designed so that every determinant is a candidate key, then that relation is in ____

A

Boyce-Codd Normal Form

71
Q

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

72
Q

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

73
Q

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

74
Q

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

75
Q

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

76
Q

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

77
Q

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

78
Q

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

79
Q

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

80
Q

The multivalued dependency noted A -> -> B, means that the value of A determines a set of values of B

81
Q

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

82
Q

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

83
Q

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

84
Q

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

85
Q

If a relation is in BCNF and each multivalued dependency has been moved to a relation of its own, then the first relation is in _____

A

Fourth Normal Form

86
Q

A relation is in forth normal form if it is in BCNF and it has no____

A

Multivalued dependencies

87
Q

A relation is in domain/key normal form if _____

A

Every constraint on the relation is a logical consequence of the definition of keys and domains

88
Q

In general, each relation should have ______

A

One and only one theme

ISE 224 (8 decks)

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