CHAPTER 3: THE RELATIONAL DATABASE MODEL
1. The practical significance of taking the logical view of a database is that it serves as a reminder of the simple
file concept of data storage.
a. True
b. False
2. You can think of a table as a persistent representation of a logical relation.
a. True
b. False
3. The order of the rows and columns is important to the DBMS.
a. True
b. False
4. Character data can contain any character or symbol intended for mathematical manipulation.
a. True
b. False
5. The row’s range of permissible values is known as its domain.
a. True
b. False
6. Each table in a relational database must have a primary key.
a. True
b. False
7. The idea of determination is unique to the database environment.
a. True
b. False
8. Only a single attribute, not multiple attributes, can define functional dependence.
a. True
b. False
Chapter 3: The Relational Database Model
9. If the attribute (B) is functionally dependent on a composite key (A) but not on any subset of that composite
key, the attribute (B) is fully functionally dependent on (A).
a. True
b. False
10. A null is created when you press the Enter key or the Tab key to move to the next entry without making a prior
entry of any kind.
a. True
b. False
11. Depending on the sophistication of the application development software, nulls can create problems when
functions such as COUNT, AVERAGE, and SUM are used.
a. True
b. False
12. RDBMSs enforce integrity rules automatically.
a. True
b. False
13. Relational algebra defines the theoretical way of manipulating table contents using relational operators.
a. True
b. False
14. The SELECT operator yields a vertical subset of a table.
a. True
b. False
15. The DIFFERENCE operator subtracts one table from the other.
a. True
b. False
16. In a natural join, the column on which the join was made occurs twice in the new table.
a. True
b. False
Chapter 3: The Relational Database Model
17. The DIVIDE operation uses one singlecolumn table (e.g., column “a”) as the divisor and one twocolumn
table (e.g., columns “a” and “b”) as the dividend.
a. True
b. False
18. A data dictionary is sometimes described as “the database designer’s database” because it records the design
decisions about tables and their structures.
a. True
b. False
19. The one-to-many (1:M) relationship is easily implemented in the relational model by putting the foreign key of
the “1” side in the table of the “many” side as a primary key.
a. True
b. False
20. As rare as 1:1 relationships should be, certain conditions absolutely require their use.
a. True
b. False
21. logic, used extensively in mathematics, provides a framework in which an assertion (statement of fact)
can be verified as either true or false.
a. Predicate b. Database
c. Relational d. Index
22. Each table represents an attribute.
a. column b. row
c. dimension d. value
23. Date attributes contain calendar dates stored in a special format known as the date format.
a. Epoch b. calendar
c. Julian d. logical
Chapter 3: The Relational Database Model
24. In the relational model, are important because they are used to ensure that each row in a table is
uniquely identifiable.
a. relations b. keys
c. indexes d. logical structures
25. A is any key that uniquely identifies each row.
a. superkey b. special key
c. foreign key d. candidate key
26. A key can be described as a minimal superkey, a superkey without any unnecessary attributes.
a. secondary b. candidate
c. primary d. foreign
27. A is the primary key of one table that has been placed into another table to create a common attribute.
a. superkey b. composite primary key
c. candidate key d. foreign key
28. Referential dictates that the foreign key must contain values that match the primary key in the related
table, or must contain null.
a. integrity b. uniqueness
c. model d. attribute
29. A key is defined as a key that is used strictly for data retrieval purposes.
a. lookup b. foreign
c. candidate d. secondary
30. The CUSTOMER table’s primary key is CUS_CODE. The CUSTOMER primary key column has no null
entries, and all entries are unique. This is an example of integrity.
a. entity b. referential
c. relational d. null
31. The constraint can be placed on a column to ensure that every row in the table has a value for that
column.
a. UNIQUE b. NOT NULL
c. VALUE d. EMPTY
Chapter 3: The Relational Database Model
32. To be considered minimally relational, the DBMS must support the key relational operators , PROJECT,
and JOIN.
a. INTERSECT b. UNION
c. DIFFERENCE d. SELECT
33. , also known as RESTRICT, yields values for all rows found in a table that satisfy a given condition.
a. INTERSECT b. UNION
c. DIFFERENCE d. SELECT
34. returns only the attributes requested, in the order in which they are requested.
a. PROJECT b. SELECT
c. UNION d. DIFFERENCE
same or compatible domains, they are said to be .
a. intersect-compatible b. union-compatible
c. difference-compatible d. select-compatible
36. A(n) join links tables by selecting only the rows with common values in their common attribute(s).
a. attribute b. unique
c. foreign d. natural
37. are especially useful when you are trying to determine what values in related tables cause referential
integrity problems.
a. Inner joins
b. Outer joins
c. Equijoins
d. Theta joins
38. A(n) only returns matched records from the tables that are being joined.
a. outer join b. inner join
c. equijoin d. theta join
Chapter 3: The Relational Database Model
39. A contains at least all of the attribute names and characteristics for each table in the system.
a. data dictionary b. relational schema
c. logical schema d. database
40. The is actually a system-created database whose tables store the user/designer-created database
characteristics and contents.
a. database tuple b. systematic database
c. unique index d. system catalog
41. In a database context, the word indicates the use of the same attribute name to label different attributes.
a. redundancy b. homonym
c. duplicate d. synonym
42. In a database context, a(n) indicates the use of different names to describe the same attribute.
a. entity b. duplicate
c. synonym d. homonym
43. The relationship is the “relational model ideal.”
a. 1:1 b. 1:M
c. M:1 d. M:N
44. The relationship should be rare in any relational database design.
a. 1:1 b. 1:M
c. M:1 d. M:N
45. relationships can be implemented by creating a new entity in 1:M relationships with the original entities.
a. 1:N b. M:1
c. M:N d. 1:1
46. Another name for a composite entity is a(n) entity.
a. bridge b. linked
c. directive d. associative
Chapter 3: The Relational Database Model
47. A(n) is an orderly arrangement used to logically access rows in a table.
a. primary rule b. superkey
c. relationship d. index
48. When you define a table’s primary key, the DBMS automatically creates a(n) index on the primary key
column(s) you declared.
a. key b. composite
c. unique d. primary
49. According to Codd’s rule of relational database, “Application programs and ad hoc facilities are
logically unaffected when changes are made to the table structures that preserve the original table values
(changing order of columns or inserting columns).”
a. nonsubversion b. logical data independence
c. comprehensive data sublanguage d. integrity independence
50. According to Codd’s rule of relational database, “If the system supports lowlevel access to the data,
users must not be allowed to bypass the integrity rules of the database.”
a. nonsubversion b. rule zero
c. view updating d. information
51. A table is also called a(n) because the relational model’s creator, E. F. Codd, used the two terms as
synonyms.
52. In a relational table, each column has a specific range of values known as the domain.
53. In a relational model, are also used to establish relationships among tables and to ensure the integrity of
the data.
54. A primary key is a(n) key chosen to be the primary means by which rows of a table are uniquely
identified.
55. To avoid nulls, some designers use special codes, known as , to indicate the absence of some value.
Chapter 3: The Relational Database Model
56. The relational operators have the property of ; that is, the use of relational algebra operators on existing
relations (tables) produces new relations.
57. PRODUCT yields all possible pairs of rows from two tables, also known as the product.
58. is the real power behind the relational database, allowing the use of independent tables linked by
common attributes.
59. A(n) links tables on the basis of an equality condition that compares specified columns of each table.
60. A(n) provides a detailed description of all tables found within the user/designer-created database.
61. The catalog can be described as a detailed system data dictionary that describes all objects within the
database, including data about table names, the table’s creator and creation date, the number of columns in
each table, the data type corresponding to each column, index filenames, index creators, authorized users, and
access privileges.
62. The relationship is the relational database norm.
63. relationships cannot be implemented as such in the relational model.
64. If one department chair—a professor—can chair only one department, and one department can have only one
department chair. The entities PROFESSOR and DEPARTMENT exhibit a(n) relationship.
65. One characteristic of generalization hierarchies is that they are implemented as relationships.
66. The proper use of keys is crucial to controlling data redundancy.
67. Proper data design requires carefully defined and controlled data redundancies to function properly.
68. A(n) index is an index in which the index key can have only one pointer value (row) associated with it.
Chapter 3: The Relational Database Model
69. An index key can have multiple (a composite index).
70. Dr. Codd’s rule of relational database states that every value in a table is guaranteed to be accessible
through a combination of table name, primary key value, and column name.
71. What is a key and how is it important in a relational model?
72. Define entity integrity. What are the two requirements to ensure entity integrity?
73. Describe the use of null values in a database.
74. Describe the use of the INTERSECT operator.
Chapter 3: The Relational Database Model
75. Define an index. Explain the role of indexes in a relational database.