Database Processing - Chapter 3

C

53) Suppose that you need to update one value of 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 only change the value in two of the rows. You have just created an a(n) ________. A) normalization anomaly B) insertion anomaly C) update anomaly D) deletion anomaly E) removal anomaly

A

54) A table that meets the definition of a relation is in ________. A) First Normal Form B) Second Normal Form C) Third Normal Form D) Boyce-Codd Normal Form E) Fourth Normal Form

A

55) A relation is in Boyce-Codd normal form if ________. A) every determinant is a candidate key B) every determinant is a primary key C) every attribute is a candidate key D) there is more than one candidate key E) there is more than one primary key

D

56) If a table is designed so that every determinant is a candidate key, then that relation is in ________. A) First Normal Form B) Second Normal Form C) Third Normal Form D) Boyce-Codd Normal Form E) Fourth Normal Form

E

57) 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) First Normal Form B) Second Normal Form C) Third Normal Form D) Boyce-Codd Normal Form E) Fourth Normal Form

B

58) A relation is in fourth normal form if it is in BCNF and it has no ________. A) transitive dependencies B) multivalued dependencies C) partial dependencies D) deletion dependencies E) referential integrity conflicts

TRUE

(T or F) A characteristic of a relation is that the cells of the relation hold a single value.

FALSE

(T or F) A characteristic of a relation is that the rows of a relation may hold identical values.

FALSE

(T or F) 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.

TRUE

(T or F) A deletion anomaly exists when deleting data about one entity results in the loss of data about another entity.

TRUE

(T or F) A determinant of a functional dependency may or may not be unique in a relation.

TRUE

(T or F) A key can be composed of a group of attributes taken together.

TRUE

(T or F) A multivalued dependency exists when a determinant is matched to a set of values.

TRUE

(T or F) A referential integrity constraint limits the values of a foreign key.

FALSE

(T or F) A relation can have only one candidate key.

FALSE

(T or F) A relation is a three-dimensional table.

TRUE

(T or F) A relation is in 4NF when multivalued dependencies are isolated in their own relation.

TRUE

(T or F) A relation is in Boyce-Codd Normal Form (BCNF) if every determinant is a candidate key.

TRUE

(T or F) A row can be uniquely identified by a key.

FALSE

(T or F) A tuple is a group of one or more columns that uniquely identifies a row.

TRUE

(T or F) All relations are tables, but not all tables are relations.

FALSE

(T or F) Any table that meets the definition of a relation is in 2NF.

TRUE

(T or F) Attribute Y is functionally dependent on attribute X if the value of attribute X determines the value of Y.

TRUE

(T or F) Functional dependencies can involve groups of attributes.

FALSE

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

FALSE

(T or F) In the functional dependency shown as A → B, B is the determinant.

FALSE

(T or F) It is possible to have a relation that does not have a key.

TRUE

(T or F) Relations are classified into "normal forms" based on the types of modification anomalies that they are vulnerable to.

TRUE

(T or F) Surrogate keys are normally not shown on forms or reports.

FALSE

(T or F) Surrogate keys usually slow performance.

FALSE

(T or F) The columns of a relation are sometimes called "tuples."

FALSE

(T or F) The functional dependency noted as A → B means that the value of A can be determined from the value of B.

TRUE

(T or F) The multivalued dependency noted as A → → B, means that the value of A determines a set of values of B.

TRUE

(T or F) Undesirable consequences of changing the data in a relation are called "modification anomalies."

TRUE

(T or F)Breaking a relation into two relations may create the need for a referential integrity constraint to be defined between the two relations.

TRUE

(T or F)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.

E

31) 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.

C

32) 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.

A

33) A relation is also known as a(n) ________. A) table B) tuple C) relationship D) attribute E) field

C

34) A tuple is also known as a(n) ________. A) table B) relation C) row D) field E) file

D

35) An attribute is also known as a(n) ________. A) table B) relation C) row D) field E) file

B

36) 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.

C

37) 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

E

38) 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

E

39) 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.

E

40) 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.

C

41) 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.

A

42) 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

C

43) A combination of one or more columns used to identify particular rows in a relation is a(n) ________. A) record B) field C) key D) tuple E) dependency

C

44) A combination of two or more columns used to identify particular rows in a relation is a(n) ________. A) record B) field C) composite key D) foreign key E) surrogate key

D

45) A determinant that determines all the other columns in a relation is a(n) ________. A) record B) field C) foreign key D) candidate key E) surrogate key

B

46) 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

D

47) An artificial column added to a relation to serve as the primary key is a(n) ________. A) composite key B) candidate key C) foreign key D) surrogate key E) dependency

C

48) A key consisting of one or more columns that is a primary key in another relation is a(n) ________. A) composite key B) candidate key C) foreign key D) surrogate key E) dependency

C

49) Referential integrity constraints are used to limit the possible values of a(n) ________. A) composite key B) candidate key C) foreign key D) surrogate key E) dependency

D

50) A(n) ________ is used to limit the possible values of a(n) foreign key. A) composite key B) surrogate key C) functional dependency D) referential integrity constraint E) normal form

E

51) 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

D

52) If the removal of facts about one entity results in the unintentional lose 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

D

59) A relation is in domain/key normal form if ________. A) every key of the relation is a logical consequence of the definition of constraints and determinants B) every key of the relation is a logical consequence of the definition of constraints and domains C) every constraint on the relation is a logical consequence of the definition of keys and determinants D) every constraint on the relation is a logical consequence of the definition of keys and domains E) every domain of the relation is a logical consequence of the definition of keys and constraints

A

60) In general, each relation should have ________. A) one and only one theme B) one or more themes C) exactly two themes D) one or two themes E) exactly three themes

relation

61) A(n) ________ is a table composed of columns and rows.

tuple

62) In relational terms as defined by E.F. Codd, a row is called a(n) ________.

attribute

63) In relational terms as defined by E.F. Codd, a column is called a(n) ________.

functional dependency

64) A(n) ________ is a relationship between attributes such that if we know the value of one attribute, we can determine the value of the other attribute.

functionally dependent

65) If by knowing the value of A we can find the value of B, then we would say that B is ________ on A.

determinant

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

composite determinant

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

A → B; A → C

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

A → C; B → C

69) Given the functional dependency (A, B) → C, then it is not true that ________ and ________.

B → A

70) Given the functional dependency A → B, it is not necessarily true that ________.

key

71) A(n) ________ is a combination of one or more columns that is used to identify particular rows in a relation.

composite key

72) A(n) ________ is a group of attributes that uniquely identifies a row.

candidate key

73) A(n) ________ is one of a group of keys that may serve as the primary key in a relation.

primary key

74) A(n) ________ is a candidate key that has been selected to uniquely identify rows in a relation.

primary key

75) A(n) relation or table has only one ________.

surrogate key

76) A(n) ________ is an artificial column that is added to a relation to be its primary key.

foreign key

77) A(n) ________ is one or more columns in one relation that also is the primary key in another table.

referential integrity constraint

78) A(n) ________ is used to make sure the values of a foreign key match a valid value of a primary key.

modification anomalies

79) For some relations, changing the data can have undesirable consequences called ________.

normal forms

80) Relations are categorized into ________ where the categorization is based on the problems the relation has.

relation

81) Any table that meets the definition of a(n) ________ is said to be in first normal form.

1NF

82) If a table is a relation then it is in ________.

Boyce-Codd

83) A defining requirement for ________ normal form is that every determinant must be a candidate key.

determinant

84) A relation is in BCNF if every ________ is a candidate key.

candidate key

85) A relation is in BCNF if every determinant is a(n) ________.

constraint

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

domain/key

87) A relation that is in ________ normal form is assured to be free from all anomalies.

referential integrity

88) Every time we break up a relation during the normalization process, we may have to create ________ constraints.

multivalued dependencies

89) A relation is in 4NF if it is in BCNF and it has no ________.

theme

90) When designing or normalizing relations, each relation should have only one ________.