Chapter 3
14) The functional dependency noted as A → B means that the value of A can be determined from the value of B.
Answer: FALSE AACSB: Information Technology Difficulty: Easy LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept
15) In the functional dependency shown as A → B, B is the determinant.
Answer: FALSE AACSB: Information Technology Difficulty: Easy LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept
52) When designing or normalizing relations, each relation should have only one theme.
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To be able to identify possible insertion, deletion, and update anomalies in a relation Classification: Concept
41) Any table that meets the definition of a relation is said to be in first normal form (1NF).
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To be able to place a relation into BCNF normal form Classification: Concept
23) A row can be uniquely identified by a key.
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To identify primary, candidate, and composite keys Classification: Concept
27) A candidate key is one of a group of keys that may serve as the primary key in a relation.
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To identify primary, candidate, and composite keys Classification: Concept
30) A surrogate key is an artificial column that is added to a relation to be its primary key.
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To identify primary, candidate, and composite keys Classification: Concept
32) Surrogate keys are normally not shown on forms or reports.
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To identify primary, candidate, and composite keys Classification: Concept
33) A foreign key is one or more columns in one relation that also is the primary key in another table.
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To identify primary, candidate, and composite keys Classification: Concept
6) In relational terms as defined by E.F. Codd, a row is called a tuple.
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To understand alternative terminology used in describing the relational model Classification: Concept
7) In relational terms as defined by E.F. Codd, a column is called an attribute.
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To understand alternative terminology used in describing the relational model Classification: Concept
1) All relations are tables, but not all tables are relations.
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To understand basic relational terminology Classification: Concept
3) A characteristic of a relation is that the cells of the relation hold a single value.
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To understand the characteristics of relations Classification: Concept
5) A relation is a table composed of columns and rows.
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To understand the characteristics of relations Classification: Concept
11) 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.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept
13) Attribute Y is functionally dependent on attribute X if the value of attribute X determines the value of Y.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept
17) Given the functional dependency (A, B) → C, the attributes (A, B) are referred to as a composite determinant.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept
18) Given the functional dependency A → (B, C), then it is true that A → B and A → C.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept
67) Given the functional dependency (A, B) → C, then ________.
A) A and B together → C B) A → C C) B → A D) Both A and B are correct Answer: A AACSB: Information Technology Difficulty: Moderate LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept
Number Color
1 Red 2 Blue 3 White 4 Green 5 Green 6 Green
69) 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. Answer: C AACSB: Information Technology Difficulty: Difficult LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept
59) Which of the following is not true about 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) Can have two identical rows Answer: D AACSB: Information Technology Difficulty: Easy LO: To understand the characteristics of relations Classification: Concept
87) 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) Third Normal Form B) Boyce-Codd Normal Form C) Fourth Normal Form D) Domain/key normal form Answer: C AACSB: Information Technology Difficulty: Moderate LO: To be able to place a relation in fourth normal form Classification: Concept
68) Which of the following is NOT true about the functional dependency A → (X, Y)?
A) X is functionally dependent on A. B) A determines Y. C) X and Y together determine A. D) X and Y are functionally dependent on A. Answer: C AACSB: Information Technology Difficulty: Moderate LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept
83) 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 B) there are no non-key attributes determined by another non-key attribute C) every attribute is a candidate key D) every candidate key is a determinant Answer: A AACSB: Information Technology Difficulty: Moderate LO: To be able to place a relation into BCNF normal form Classification: Concept
84) A relation is in third normal form (3NF) if and only if it is in 2NF and ________.
A) all non-key attributes are determined by the entire primary key B) there are no non-key attributes determined by another non-key attribute C) every attribute is a candidate key D) every candidate key is a determinant Answer: B AACSB: Information Technology Difficulty: Moderate LO: To be able to place a relation into BCNF normal form Classification: Concept
85) A relation is in Boyce-Codd normal form (BCNF) if and only if it is in 3NF and ________.
A) all non-key attributes are determined by the entire primary key B) there are no non-key attributes determined by another non-key attribute C) every attribute is a candidate key D) every determinant is a candidate key Answer: D AACSB: Information Technology Difficulty: Moderate LO: To be able to place a relation into BCNF normal form Classification: Concept 86) 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 Answer: D AACSB: Information Technology Difficulty: Moderate LO: To be able to place a relation into BCNF normal form Classification: Concept
76) 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 Answer: C AACSB: Information Technology Difficulty: Moderate LO: To identify primary, candidate, and composite keys Classification: Concept
77) Referential integrity constraints are used to limit the possible values of a ________.
A) composite key B) candidate key C) foreign key D) surrogate key Answer: C AACSB: Information Technology Difficulty: Moderate LO: To identify primary, candidate, and composite keys Classification: Concept 78) 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 Answer: D AACSB: Information Technology Difficulty: Moderate LO: To identify primary, candidate, and composite keys Classification: Concept
75) 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 Answer: D AACSB: Information Technology Difficulty: Easy LO: To identify primary, candidate, and composite keys Classification: Concept
89) 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 Answer: D AACSB: Information Technology Difficulty: Moderate LO: To understand the special importance of domain/key normal form Classification: Concept 90) 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 Answer: A AACSB: Information Technology Difficulty: Easy LO: To understand the characteristics of relations Classification: Concept
65) Given the functional dependency A → (B, C), A is a(n) ________.
A) independent variable B) dependent variable C) determinant D) composite determinant Answer: C AACSB: Information Technology Difficulty: Moderate LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept 66) Given the functional dependency (A, B) → C, (A, B) is a ________. A) dependent variable B) determinant C) composite determinant D) Both B and C are correct Answer: D AACSB: Information Technology Difficulty: Moderate LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept
79) Having to enter facts about two entities when we want to enter facts about only one is an example of ________.
A) insertion anomaly B) update anomaly C) deletion anomaly D) normalization anomaly Answer: A AACSB: Information Technology Difficulty: Moderate LO: To be able to identify possible insertion, deletion, and update anomalies in a relation Classification: Concept
35) 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.
Answer: FALSE AACSB: Information Technology Difficulty: Difficult LO: To identify primary, candidate, and composite keys Classification: Concept
81) Suppose that you need to update one value of the column SalesCost in a relation. The way the relation is constructed, this value needs to be changed in three different rows. However, you only change the value in two of the rows. You have just created a(n) ________.
A) normalization anomaly B) insertion anomaly C) update anomaly D) deletion anomaly Answer: C AACSB: Information Technology Difficulty: Moderate LO: To be able to identify possible insertion, deletion, and update anomalies in a relation Classification: Concept 82) 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 Answer: A AACSB: Information Technology Difficulty: Easy LO: To be able to identify possible insertion, deletion, and update anomalies in a relation Classification: Concept
71) A combination of one or more columns used to identify rows in a relation is a ________.
A) record B) field C) key D) tuple Answer: C AACSB: Information Technology Difficulty: Easy LO: To identify primary, candidate, and composite keys Classification: Concept
73) A determinant that determines all the other columns in a relation is a ________.
A) record B) surrogate key C) foreign key D) candidate key Answer: D AACSB: Information Technology Difficulty: Easy LO: To identify primary, candidate, and composite keys Classification: Concept 74) 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 Answer: B AACSB: Information Technology Difficulty: Easy LO: To identify primary, candidate, and composite keys Classification: Concept
70) The only reason(s) for having relations is to ________.
A) store instances of functional dependencies B) store equation components C) store equation results D) Both B and C are correct Answer: A AACSB: Information Technology Difficulty: Moderate LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept
63) An attribute is also known as a ________.
A) table B) relation C) row D) column Answer: D AACSB: Information Technology Difficulty: Easy LO: To understand alternative terminology used in describing the relational model Classification: Concept
62) A tuple is also known as a ________.
A) table B) relation C) row D) field Answer: C AACSB: Information Technology Difficulty: Easy LO: To understand alternative terminology used in describing the relational model Classification: Concept
61) A relation is also known as a(n) ________.
A) table B) tuple C) relationship D) attribute Answer: A AACSB: Information Technology Difficulty: Easy LO: To understand alternative terminology used in describing the relational model Classification: Concept
64) 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 entities, if we are given the value of one entity, we can determine the value of the other entity D) the functional dependency will have to be removed through normalization Answer: B AACSB: Information Technology Difficulty: Moderate LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept
In this case, Number functionally determines Color, written as Number → Color. Then, if we know the Number is 3, we know the Color is White. Note that the reverse is not true—Color does not determine Number since if we are given the Color Green the number could be 4, 5, or 6. The attribute on the left-hand side of the dependency is called the "determinant." Thus, Number is a determinant. Although equations can be expressed as functional dependencies [as when the equation TotalCost = NumberSold * ItemCost is written as the functional dependency (NumberSold, ItemCost) → TotalCost] functional dependencies are not equations. Also note that a determinant can have more than one attribute [as does (NumberSold, ItemCost) in the last example] and when it does it is called a composite determinant.
AACSB: Information Technology Difficulty: Easy LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Application
94) Distinguish between the primary key and a candidate key.
Answer: Both the primary key and a candidate key can uniquely identify the rows in a table. The primary key is the candidate key that is chosen by the database designer, working with the users, to uniquely identify rows and to represent relationships. Although any candidate key could, by definition, be selected to act as the primary key, the choice of primary key is often based on design decisions such as the amount of foreign key data that would be generated. AACSB: Information Technology Difficulty: Easy LO: To identify primary, candidate, and composite keys Classification: Concept
47) Candidate keys are called interlocking candidate keys when they share one or more attributes.
Answer: FALSE AACSB: Information Technology Difficulty: Difficult LO: To be able to place a relation into BCNF normal form Classification: Concept
26) It is possible to have a relation that does not have a key.
Answer: FALSE AACSB: Information Technology Difficulty: Difficult LO: To identify primary, candidate, and composite keys Classification: Concept
42) Any table that meets the definition of a relation is in 2NF.
Answer: FALSE AACSB: Information Technology Difficulty: Easy LO: To be able to place a relation into BCNF normal form Classification: Concept 43) 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. Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To be able to place a relation into BCNF normal form Classification: Concept
24) A combination key is a group of attributes that uniquely identifies a row.
Answer: FALSE AACSB: Information Technology Difficulty: Easy LO: To identify primary, candidate, and composite keys Classification: Concept
8) The columns of a relation are sometimes called tuples.
Answer: FALSE AACSB: Information Technology Difficulty: Easy LO: To understand alternative terminology used in describing the relational model Classification: Concept
9) A tuple is a group of one or more columns that uniquely identifies a row.
Answer: FALSE AACSB: Information Technology Difficulty: Easy LO: To understand alternative terminology used in describing the relational model Classification: Concept
2) A relation is a table that has special restrictions on it.
Answer: FALSE AACSB: Information Technology Difficulty: Easy LO: To understand the characteristics of relations Classification: Concept
20) Given the functional dependency A → B, then it is necessarily true that B → A.
Answer: FALSE AACSB: Information Technology Difficulty: Moderate LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept
37) If a table meets the minimum definition of a relation, it has an effective or appropriate structure.
Answer: FALSE AACSB: Information Technology Difficulty: Moderate LO: To be able to identify possible insertion, deletion, and update anomalies in a relation Classification: Concept
28) A relation can have only one candidate key.
Answer: FALSE AACSB: Information Technology Difficulty: Moderate LO: To identify primary, candidate, and composite keys Classification: Concept 29) A primary key is a candidate key that has been selected to uniquely identify rows in a relation. Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To identify primary, candidate, and composite keys Classification: Concept
4) A characteristic of a relation is that the rows of a relation may hold identical values.
Answer: FALSE AACSB: Information Technology Difficulty: Moderate LO: To understand the characteristics of relations Classification: Concept
92) Describe the requirements that a table must meet to qualify as a relation.
Answer: For a table to meet the requirements of a relation, it must satisfy certain conditions. First, the rows contain data about an entity or some portion of the entity. Second, the columns contain data that represent attributes of the entity. Third, each column must contain the same kind of data for all rows. Fifth, each column must have a unique name. Sixth, the cells must contain single values—no group or array values are allowed. Seventh, the order of the columns and the rows is insignificant. Finally, the rows must be unique. AACSB: Information Technology Difficulty: Easy LO: To understand the characteristics of relations Classification: Concept 93) Explain the terms relation, tuple, and attribute. Answer: The terms relation, tuple, and attribute are used primarily by database theoreticians. These terms are synonymous with the terms table, row, and column, respectively, in regards to a relational database. They are also equivalent to the terms file, record, and field, which tend to be used by many traditional data processing professionals. AACSB: Information Technology Difficulty: Easy LO: To understand alternative terminology used in describing the relational model Classification: Concept
96) Explain the relationships among primary keys and functional dependencies.
Answer: Relations store instances of functional dependencies in their rows. All primary keys represent a functional dependency, since each primary key functionally determines the entire row. Since the primary key determines the entire row, if a primary key were duplicated in a relation, then the entire row would have to be duplicated. Since a relation can contain no duplicate rows, the primary key must be unique. AACSB: Information Technology Difficulty: Difficult LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Synthesis
45) The condition that a non-key attribute determines another non-key attribute is known as transitive dependency.
Answer: TRUE AACSB: Information Technology Difficulty: Difficult LO: To be able to place a relation into BCNF normal form Classification: Concept
46) An attribute is a non-key attribute when it is a non-prime attribute, which means that the attribute is not contained in any candidate key.
Answer: TRUE AACSB: Information Technology Difficulty: Difficult LO: To be able to place a relation into BCNF normal form Classification: Concept
10) 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.
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept
12) In functional dependencies, the attribute whose value is known or given is referred to as the determinant.
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept
16) Functional dependencies can involve groups of attributes.
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept
54) The multivalued dependency noted as A → → B, means that the value of A determines a set of values of B.
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To be able to identify multivalued dependencies Classification: Concept
39) A deletion anomaly exists when deleting data about one entity results in the loss of data about another entity.
Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To be able to identify possible insertion, deletion, and update anomalies in a relation Classification: Concept
21) A determinant of a functional dependency may or may not be unique in a relation.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To be able to identify functional dependencies, determinants, and dependent attributes Classification: Concept 22) A key is a combination of one or more columns that is used to identify particular rows in a relation. Answer: TRUE AACSB: Information Technology Difficulty: Easy LO: To identify primary, candidate, and composite keys Classification: Concept
53) A multivalued dependency exists when a determinant is matched to a set of values.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To be able to identify multivalued dependencies Classification: Concept
55) A relation is in 4NF when multivalued dependencies are isolated in their own relation.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To be able to identify multivalued dependencies Classification: Concept
56) A relation is in 4NF if it is in BCNF and it has no multivalued dependencies.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To be able to identify multivalued dependencies Classification: Concept
38) Undesirable consequences of changing the data in a relation are called modification anomalies.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To be able to identify possible insertion, deletion, and update anomalies in a relation Classification: Concept
40) Relations are classified into normal forms based on the types of modification anomalies that they are vulnerable to.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To be able to identify possible insertion, deletion, and update anomalies in a relation Classification: Concept
49) A relation is in Boyce Codd Normal Form (BCNF) if and only if it is in 3NF and every determinant is a candidate key.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To be able to place a relation into BCNF Classification: Concept
44) 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.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To be able to place a relation into BCNF normal form Classification: Concept
48) A relation is in Boyce-Codd Normal Form (BCNF) if and only if it is in 3NF and every determinant is a candidate key.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To be able to place a relation into BCNF normal form Classification: Concept
50) Every time we break up a relation during the normalization process, we may have to create a referential integrity constraint.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To be able to place a relation into BCNF normal form Classification: Concept
51) 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.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To be able to place a relation into BCNF normal form Classification: Concept
34) A referential integrity constraint is used to make sure the values of a foreign key match a valid value of a primary key.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To identify primary, candidate, and composite keys Classification: Concept
36) A referential integrity constraint limits the values of a foreign key.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To identify primary, candidate, and composite keys Classification: Concept
57) Domain/key normal form requires that every constraint be a logical consequence of the definition of domains and keys.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To understand the special importance of domain/key normal form Classification: Concept
58) A relation that is in domain/key normal form is assured to be free from all anomalies.
Answer: TRUE AACSB: Information Technology Difficulty: Moderate LO: To understand the special importance of domain/key normal form Classification: Concept
99) Explain the essence of normalization that is implemented using normal forms.
Answer: The essence of normalization is to create relations that contain data on a single theme, and for each row in a relation to contain all the data about that theme for a given entity. This essence is implemented in the normal forms by taking a relation that contains data on more than one theme and splitting it into multiple relations that each contains data on a single theme. The different normal forms protect against the occurrence of modification anomalies. In practice, making sure all relations are in Boyce-Codd Normal Form (BCNF), or in Fourth Normal Form (4NF) if multivalued dependencies are found, insures high reliability of the database. AACSB: Information Technology Difficulty: Difficult LO: To be able to place a relation into BCNF normal form Classification: Application
95) Briefly describe the various tasks of the primary key.
Answer: The primary key is used for four primary tasks. First, it is used to uniquely identify the rows in a table. Second, it is used to represent rows in relationships. Third, most DBMS products use the values of the primary key to organize the storage of the relation. Finally, primary keys are used in indexes and other structures to improve performance for search operations. AACSB: Information Technology Difficulty: Moderate LO: To identify primary, candidate, and composite keys Classification: Concept
