(Thursday, June 7, 2007-)
+7:42 AM]*
+7:42 AM]*
# -
True/False
Indicate whether the statement is true or false.
1. You can select partial table contents by naming the desired fields and by placing restrictions on the rows to be included in the output. (T)
2. To list the contents of a table, you must use the DISPLAY command. (F)
3. All simple attributes are also single-valued. (F)
4. Derived attributes are stored in a special database table. (F)
5. The ANSI prescribes a standard SQL–the most recent version is known as SQL-99. (T)
6. Normalization produces a lower normal form. (F)
7. Date procedures are often more software-specific than most other SQL
procedures. (T)
8. The ER model refers to a specific table row as an entity instance. (T)
9. Data redundancies are caused by the fact that every row entry requires duplication of data. (T)
10. Normalization is a very important database design ingredient and the highest level is always the most desirable. (F)
11. Denormalization is a process for assigning attributes to entities. (F)
12. A subtype discriminator is the attribute in the supertype entity that determines to which entity subtype each supertype occurrence is related. (T)
13. All entity relationships can be characterized as weak or strong. (T)
14. A data modeler uses a composite primary as the primary key of the entity being modeled. (F)
15. Because a partial dependency can exist only if a table's primary key is composed of several attributes, a table whose primary key consists of only a single attribute must automatically be in 2NF if it is in 1NF. (T)
16. The specialization hierarchy depicts the arrangement of higher-level entity supertypes (parent entities) and lower-level entity subtypes (child entities). (T)
17. In non-overlapping subtypes,each entity instance of the supertype can not appear in more than one subtype. (T)
18. Normalization is a process that is used for changing attributes to entities. (F)
19. The entity supertype contains the common characteristics and the entity subtypes contain the unique characteristics of each entity subtype. (T)
20. Some designs use redundant relationships as a way to simplify the design. (T)
21. Because COUNT is designed to tally the number of non-null "values" of an attribute, it is used in conjunction with the DISTINCT clause. (T)
22. The conditional LIKE must be used in conjunction with wildcard characters. (T)
23. In Chen notation, there is no way to represent cardinality. (F)
24. The ER model is used to expand the different views of the data at the conceptual level. (F)
25. At the implementation level, the supertype and its subtype(s) depicted in the specialization hierarchy maintain a 1:1 relationship. (T)
26. Specialization is the top-down process of identifying lower-level, more specific entity subtypes from a higher-level entity supertype. (T)
27. The SQL commands may be issued on a single line, but command sequences are best structured when the SQL command's components are shown on separate and indented lines. (T)
28. The completeness constraint can be partial or total. (T)
29. Only numeric data can be added and subtracted, not other data types. (F)
30. Dependencies can be identified with the help of the dependency diagram. (T)
31. ANSI-standard SQL allows the use of special operators in conjunction with the
WHERE clause. (T)
32. Ideally, a primary key is composed of several attributes. (F)
33. A composite key is a primary key composed of more than one attribute. (T)
34. All attributes are either simple or composite. (T)
35. Atomic attributes are attributes that can be further divided. (F)
36. A relational table must contain repeating groups. (F)
37. In any case, keeping the history of time-variant data is equivalent to having a multivalued attribute in your entity. To model time-variant data, you must create a new entity in a 1:M relationship with the original entity. (T)
38. All relational tables satisfy the 1NF requirements. (T)
39. You cannot insert a row containing a null attribute value using SQL. (F)
40. Attributes may not share a domain. (F)
Multiple Choice
Identify the choice that best completes the statement or answers the question.
41. The conflicts between design efficiency, information requirements, and processing speed are often resolved through ____.
a. conversion from 3NF to 4NF
b. conversion from 2NF to 3NF
c. compromises that include denormalization
d. conversion from 1NF to 2NF
42. A table where all attributes are dependent on the primary key and are independent of each other, and no row
contains two or more multivalued facts about an entity, is said to be in ____.
a. 1NF
b. 2NF
c. 3NF
d. 4NF
43. SQL character data format is/are ____.
a. Alphanumeric
b. CHAR only
c. VARCHAR only
d. CHAR and VARCHAR
44. A ____ relationship exists when three entities are associated.
a. weak
b. ternary
c. binary
d. unary
45. A ____ attribute is one that cannot be subdivided.
a. single-valued
b. multivalued
c. simple
d. composite
46. Which of the following should be a derived attribute?
a. Person’s name
b. Person’s age
c. Person’s social security number
d. Person’s phone number
47. The ____ model is the end user's view of the data environment.
a. conceptual
b. physical
c. external
d. internal
48. Which query will output the table contents when the value of V_CODE is less than or equal to 21344?
a. SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE = 21344;
b. SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE <> 21344;
c. SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE => 21344;
d. SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE <=21344;
49. The term “____” is used to label any condition in which one or more optional relationships exist.
a. cardinality
b. optionality
c. participation
d. connectivity
50. What happens when you issue the DELETE FROM tablename command without specifying a where condition?
a. the last row will be deleted
b. the first row will be deleted
c. no rows will be deleted
d. all rows will be deleted
51. Which command uses columns and column aliases to determine the total value of inventory held on hand?
a. SELECT P_DESCRIPT, P_QOH, P_PRICE, P_ONHAND=P_PRICE
FROM PRODUCT;
b. SELECT P_DESCRIPT, P_QOH, P_PRICE, P_ONHAND-P_PRICE
FROM PRODUCT;
c. SELECT P_DESCRIPT, P_QOH, P_PRICE, P_ONHAND/P_PRICE
FROM PRODUCT;
d. SELECT P_DESCRIPT, P_QOH, P_PRICE, P_QOH*P_PRICE
FROM PRODUCT;
52. A ____ is the attribute in the supertype entity that determines to which entity subtype each supertype occurrence is related.
a. specialization hierarchy
b. inheritance
c. entity supertype
d. subtype discriminator
53. What is the SQL syntax requirement to list the table contents for either V_CODE = 21344 or V_CODE = 24288?
a. SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE = 21344
OR V_CODE => 24288
b. SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE = 21344
OR V_CODE > 24288
c. SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE = 21344
OR V_CODE = 24288
d. SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE = 21344
OR V_CODE <= 24288
54. Overlapping subtypes are subtypes that contain ____ subsets of the supertype entity set.
a. subtypes
b. nonunique
c. entity
d. unique
55. What is the command to join the P_DESCRIPT and P_PRICE fields from the PRODUCT table and the V_NAME, V_AREACODE, V_PHONE, and V_CONTACT fields from the VENDOR table where the value of V_CODE match?
a. SELECT P_DESCRIPT, P_PRICE, V_NAME, V_CONTACT, V_AREACODE, V_PHONE
FROM PRODUCT, VENDOR
WHERE PRODUCT.V_CODE <= VENDOR.V_CODE;
b. SELECT P_DESCRIPT, P_PRICE, V_NAME, V_CONTACT, V_AREACODE, V_PHONE
FROM PRODUCT, VENDOR
WHERE PRODUCT.V_CODE => VENDOR.V_CODE;
c. SELECT P_DESCRIPT, P_PRICE, V_NAME, V_CONTACT, V_AREACODE, V_PHONE
FROM PRODUCT, VENDOR
WHERE PRODUCT.V_CODE <> VENDOR.V_CODE;
d. SELECT P_DESCRIPT, P_PRICE, V_NAME, V_CONTACT, V_AREACODE, V_PHONE
FROM PRODUCT, VENDOR
WHERE PRODUCT.V_CODE = VENDOR.V_CODE;
56. The bridge entity is known as a ____ entity.
a. weak
b. unary
c. composite
d. strong
57. When designing a database, you should ____.
a. create table structures then normalize the database
b. consider more important issues such as performance before normalizing
c. make sure entities are in normal form before table structures are created
d. only normalize the database when performance problems occur
58. A dependency diagram is useful for all of the following except:
a. getting a bird's eye view of all of the relationships among a table's attributes
b. adding additional attributes to the table
c. depicting all dependencies found within a given table structure
d. making it less likely that you will overlook an important dependency
59. Granularity refers to:
a. the size of a table
b. the level of detail represented by the values stored in a table's row
c. the number of rows in a table
d. the number of attributes in a table
60. The SQL command that enables you to make changes in the data is ____.
a. COMMIT
b. UPDATE
c. INSERT
d. SELECT
61. ____ is used to tally the number of specific "values" of an attribute.
a. TOTAL
b. ADD
c. COUNT
d. SUM
62. The PK must uniquely identify each entity instance. A primary key must be able to guarantee unique values. It cannot contain nulls.This rationale belongs to ____.
a. Nonintelligent
b. Security complaint
c. Unique values
d. Preferably single-attribute
63. ANSI-standard SQL allows the use of special operators in conjunction with the WHERE clause. A special operator used to check whether an attribute value is null is ____.
a. IN
b. LIKE
c. IS NULL
d. BETWEEN
64. In BCNF, every ____ in a table is a candidate key.
a. determinant
b. primary key
c. atomic attribute
d. entity
65. The ____ depicts the arrangement of higher-level entity supertypes (parent entities) and lower-level entity
subtypes (child entities).
a. entity supertype
b. inheritance
c. specialization hierarchy
d. subtype discriminator
66. A derived attribute ____.
a. need not be physically stored within the database
b. must be stored physically within the database
c. has many values
d. must be based on the value of three or more attributes
67. Normalization works through a series of stages called normal forms. Typically ____ stages are processed.
a. 2
b. 3
c. 4
d. 5
68. For most business transactional databases, we should normalize relations into:
a. 1NF
b. 3NF
c. 2NF
d. 6NF
69. In the Chen model, cardinality is indicated using the ____ notation.
a. (min, max)
b. {min|max}
c. [min ... max]
d. (max, min)
70. Cardinality expresses ____ number of entity occurrences associated with one occurrence of the related entity.
a. an undetermined
b. a programmed
c. the specific
d. a pre-determined
71. A specialization hierarchy can have ____ levels of supertype/subtype relationships.
a. none
b. one or many
c. many
d. only one
72. One important inheritance characteristic is that all entity subtypes inherit their ____ attribute from their supertype.
a. foreign key
b. natural key
c. Surrogate key
d. primary key
73. Surrogate primary keys are especially helpful when there is no ____.
a. natural key
b. foreign key
c. primary key
d. Surrogate key
74. An entity cluster is formed by combining multiple interrelated entities into ____.
a. multiple entity object
b. a single entity object
c. multiple abstract entity object
d. a single abstract entity object
75. ____ yields better performance.
a. Atomization
b. Compression
c. Denormalization
d. Normalization
76. The extended entity relationship model (EERM) is sometimes referred to as the ____.
a. extended entity relationship diagram
b. entity clustering relationship model
c. entity relationship model
d. enhanced entity relationship model
77. Improving ____ leads to more flexible queries.
a. denormalization
b. atomicity
c. normalization
d. derived attributes
78. If an entity’s existence depends on the existence of one or more other entities, it is said to be
_____-dependent.
a. existence
b. relationship
c. weak
d. business
79. At the implementation level, the supertype and its subtype(s) depicted in the specialization hierarchy maintain a ____ relationship.
a. none
b. 1:1
c. 1:M
d. M:N
80. ANSI-standard SQL allows the use of special operators in conjunction with the WHERE clause. A special operator used to check whether an attribute value matches a value contained within a subset of listed values is ____.
a. IS NULL
b. BETWEEN
c. IN
d. LIKE
Complete each statement.
81. From a data modeling point of view, time-variant data refer to data whose values change over time and for which you must keep a history of the data changes.
82. SQL has a basic vocabulary of fewer than 100 words.
83. Disjoint subtypes, also known as non-overlapping subtypes , are subtypes that contain a unique subset of the supertype entity set.
84. The primary key main function is to uniquely identify an entity instance or row within a table.
85. A(n) natural key or natural identifier is a real-world, generally accepted identifier used to distinguish that is, uniquely identify real-world objects.
86. The ER model refers to a specific table row as an entity instance.
87. Frequency distributions can be created quickly and easily using the SQL GROUP BY clause.
88. The specialization hierarchy depicts the arrangement of higher-level entity supertypes (parent entities) and lower-level entity subtypes (child entities).
89. A(n) domain is the attribute’s set of possible values.
90. To restore the values of a table, provided you have not used the COMMIT command, you must use the ROLLBACK command.
91. A relational table must not contain repeating groups.
92. Relationship strength depends on how the primary key of the related entity is formulated, while the relationship participation depends on how the business rule is written.
93. SQL allows the use of logical restrictions on its inquiries using OR, AND, and NOT.
94. Partial completeness means some supertype occurrences that are not members of any subtype.
95. In the relationship “EMPLOYEE claims DEPENDENT” the DEPENDENT entity is
existence-dependent on the EMPLOYEE entity.
96. An attribute representing one or more college degrees belonging to a person would be a(n)
multivalued attribute.
97. Primary keys are underlined in an ER diagram.
98. A(n) join is performed when data is retrieved from more than one table at a time.
99. Any changes made to the table contents are not physically saved on disk until you use the
COMMIT command.
Indicate whether the statement is true or false.
1. You can select partial table contents by naming the desired fields and by placing restrictions on the rows to be included in the output. (T)
2. To list the contents of a table, you must use the DISPLAY command. (F)
3. All simple attributes are also single-valued. (F)
4. Derived attributes are stored in a special database table. (F)
5. The ANSI prescribes a standard SQL–the most recent version is known as SQL-99. (T)
6. Normalization produces a lower normal form. (F)
7. Date procedures are often more software-specific than most other SQL
procedures. (T)
8. The ER model refers to a specific table row as an entity instance. (T)
9. Data redundancies are caused by the fact that every row entry requires duplication of data. (T)
10. Normalization is a very important database design ingredient and the highest level is always the most desirable. (F)
11. Denormalization is a process for assigning attributes to entities. (F)
12. A subtype discriminator is the attribute in the supertype entity that determines to which entity subtype each supertype occurrence is related. (T)
13. All entity relationships can be characterized as weak or strong. (T)
14. A data modeler uses a composite primary as the primary key of the entity being modeled. (F)
15. Because a partial dependency can exist only if a table's primary key is composed of several attributes, a table whose primary key consists of only a single attribute must automatically be in 2NF if it is in 1NF. (T)
16. The specialization hierarchy depicts the arrangement of higher-level entity supertypes (parent entities) and lower-level entity subtypes (child entities). (T)
17. In non-overlapping subtypes,each entity instance of the supertype can not appear in more than one subtype. (T)
18. Normalization is a process that is used for changing attributes to entities. (F)
19. The entity supertype contains the common characteristics and the entity subtypes contain the unique characteristics of each entity subtype. (T)
20. Some designs use redundant relationships as a way to simplify the design. (T)
21. Because COUNT is designed to tally the number of non-null "values" of an attribute, it is used in conjunction with the DISTINCT clause. (T)
22. The conditional LIKE must be used in conjunction with wildcard characters. (T)
23. In Chen notation, there is no way to represent cardinality. (F)
24. The ER model is used to expand the different views of the data at the conceptual level. (F)
25. At the implementation level, the supertype and its subtype(s) depicted in the specialization hierarchy maintain a 1:1 relationship. (T)
26. Specialization is the top-down process of identifying lower-level, more specific entity subtypes from a higher-level entity supertype. (T)
27. The SQL commands may be issued on a single line, but command sequences are best structured when the SQL command's components are shown on separate and indented lines. (T)
28. The completeness constraint can be partial or total. (T)
29. Only numeric data can be added and subtracted, not other data types. (F)
30. Dependencies can be identified with the help of the dependency diagram. (T)
31. ANSI-standard SQL allows the use of special operators in conjunction with the
WHERE clause. (T)
32. Ideally, a primary key is composed of several attributes. (F)
33. A composite key is a primary key composed of more than one attribute. (T)
34. All attributes are either simple or composite. (T)
35. Atomic attributes are attributes that can be further divided. (F)
36. A relational table must contain repeating groups. (F)
37. In any case, keeping the history of time-variant data is equivalent to having a multivalued attribute in your entity. To model time-variant data, you must create a new entity in a 1:M relationship with the original entity. (T)
38. All relational tables satisfy the 1NF requirements. (T)
39. You cannot insert a row containing a null attribute value using SQL. (F)
40. Attributes may not share a domain. (F)
Multiple Choice
Identify the choice that best completes the statement or answers the question.
41. The conflicts between design efficiency, information requirements, and processing speed are often resolved through ____.
a. conversion from 3NF to 4NF
b. conversion from 2NF to 3NF
c. compromises that include denormalization
d. conversion from 1NF to 2NF
42. A table where all attributes are dependent on the primary key and are independent of each other, and no row
contains two or more multivalued facts about an entity, is said to be in ____.
a. 1NF
b. 2NF
c. 3NF
d. 4NF
43. SQL character data format is/are ____.
a. Alphanumeric
b. CHAR only
c. VARCHAR only
d. CHAR and VARCHAR
44. A ____ relationship exists when three entities are associated.
a. weak
b. ternary
c. binary
d. unary
45. A ____ attribute is one that cannot be subdivided.
a. single-valued
b. multivalued
c. simple
d. composite
46. Which of the following should be a derived attribute?
a. Person’s name
b. Person’s age
c. Person’s social security number
d. Person’s phone number
47. The ____ model is the end user's view of the data environment.
a. conceptual
b. physical
c. external
d. internal
48. Which query will output the table contents when the value of V_CODE is less than or equal to 21344?
a. SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE = 21344;
b. SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE <> 21344;
c. SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE => 21344;
d. SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE <=21344;
49. The term “____” is used to label any condition in which one or more optional relationships exist.
a. cardinality
b. optionality
c. participation
d. connectivity
50. What happens when you issue the DELETE FROM tablename command without specifying a where condition?
a. the last row will be deleted
b. the first row will be deleted
c. no rows will be deleted
d. all rows will be deleted
51. Which command uses columns and column aliases to determine the total value of inventory held on hand?
a. SELECT P_DESCRIPT, P_QOH, P_PRICE, P_ONHAND=P_PRICE
FROM PRODUCT;
b. SELECT P_DESCRIPT, P_QOH, P_PRICE, P_ONHAND-P_PRICE
FROM PRODUCT;
c. SELECT P_DESCRIPT, P_QOH, P_PRICE, P_ONHAND/P_PRICE
FROM PRODUCT;
d. SELECT P_DESCRIPT, P_QOH, P_PRICE, P_QOH*P_PRICE
FROM PRODUCT;
52. A ____ is the attribute in the supertype entity that determines to which entity subtype each supertype occurrence is related.
a. specialization hierarchy
b. inheritance
c. entity supertype
d. subtype discriminator
53. What is the SQL syntax requirement to list the table contents for either V_CODE = 21344 or V_CODE = 24288?
a. SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE = 21344
OR V_CODE => 24288
b. SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE = 21344
OR V_CODE > 24288
c. SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE = 21344
OR V_CODE = 24288
d. SELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE
FROM PRODUCT
WHERE V_CODE = 21344
OR V_CODE <= 24288
54. Overlapping subtypes are subtypes that contain ____ subsets of the supertype entity set.
a. subtypes
b. nonunique
c. entity
d. unique
55. What is the command to join the P_DESCRIPT and P_PRICE fields from the PRODUCT table and the V_NAME, V_AREACODE, V_PHONE, and V_CONTACT fields from the VENDOR table where the value of V_CODE match?
a. SELECT P_DESCRIPT, P_PRICE, V_NAME, V_CONTACT, V_AREACODE, V_PHONE
FROM PRODUCT, VENDOR
WHERE PRODUCT.V_CODE <= VENDOR.V_CODE;
b. SELECT P_DESCRIPT, P_PRICE, V_NAME, V_CONTACT, V_AREACODE, V_PHONE
FROM PRODUCT, VENDOR
WHERE PRODUCT.V_CODE => VENDOR.V_CODE;
c. SELECT P_DESCRIPT, P_PRICE, V_NAME, V_CONTACT, V_AREACODE, V_PHONE
FROM PRODUCT, VENDOR
WHERE PRODUCT.V_CODE <> VENDOR.V_CODE;
d. SELECT P_DESCRIPT, P_PRICE, V_NAME, V_CONTACT, V_AREACODE, V_PHONE
FROM PRODUCT, VENDOR
WHERE PRODUCT.V_CODE = VENDOR.V_CODE;
56. The bridge entity is known as a ____ entity.
a. weak
b. unary
c. composite
d. strong
57. When designing a database, you should ____.
a. create table structures then normalize the database
b. consider more important issues such as performance before normalizing
c. make sure entities are in normal form before table structures are created
d. only normalize the database when performance problems occur
58. A dependency diagram is useful for all of the following except:
a. getting a bird's eye view of all of the relationships among a table's attributes
b. adding additional attributes to the table
c. depicting all dependencies found within a given table structure
d. making it less likely that you will overlook an important dependency
59. Granularity refers to:
a. the size of a table
b. the level of detail represented by the values stored in a table's row
c. the number of rows in a table
d. the number of attributes in a table
60. The SQL command that enables you to make changes in the data is ____.
a. COMMIT
b. UPDATE
c. INSERT
d. SELECT
61. ____ is used to tally the number of specific "values" of an attribute.
a. TOTAL
b. ADD
c. COUNT
d. SUM
62. The PK must uniquely identify each entity instance. A primary key must be able to guarantee unique values. It cannot contain nulls.This rationale belongs to ____.
a. Nonintelligent
b. Security complaint
c. Unique values
d. Preferably single-attribute
63. ANSI-standard SQL allows the use of special operators in conjunction with the WHERE clause. A special operator used to check whether an attribute value is null is ____.
a. IN
b. LIKE
c. IS NULL
d. BETWEEN
64. In BCNF, every ____ in a table is a candidate key.
a. determinant
b. primary key
c. atomic attribute
d. entity
65. The ____ depicts the arrangement of higher-level entity supertypes (parent entities) and lower-level entity
subtypes (child entities).
a. entity supertype
b. inheritance
c. specialization hierarchy
d. subtype discriminator
66. A derived attribute ____.
a. need not be physically stored within the database
b. must be stored physically within the database
c. has many values
d. must be based on the value of three or more attributes
67. Normalization works through a series of stages called normal forms. Typically ____ stages are processed.
a. 2
b. 3
c. 4
d. 5
68. For most business transactional databases, we should normalize relations into:
a. 1NF
b. 3NF
c. 2NF
d. 6NF
69. In the Chen model, cardinality is indicated using the ____ notation.
a. (min, max)
b. {min|max}
c. [min ... max]
d. (max, min)
70. Cardinality expresses ____ number of entity occurrences associated with one occurrence of the related entity.
a. an undetermined
b. a programmed
c. the specific
d. a pre-determined
71. A specialization hierarchy can have ____ levels of supertype/subtype relationships.
a. none
b. one or many
c. many
d. only one
72. One important inheritance characteristic is that all entity subtypes inherit their ____ attribute from their supertype.
a. foreign key
b. natural key
c. Surrogate key
d. primary key
73. Surrogate primary keys are especially helpful when there is no ____.
a. natural key
b. foreign key
c. primary key
d. Surrogate key
74. An entity cluster is formed by combining multiple interrelated entities into ____.
a. multiple entity object
b. a single entity object
c. multiple abstract entity object
d. a single abstract entity object
75. ____ yields better performance.
a. Atomization
b. Compression
c. Denormalization
d. Normalization
76. The extended entity relationship model (EERM) is sometimes referred to as the ____.
a. extended entity relationship diagram
b. entity clustering relationship model
c. entity relationship model
d. enhanced entity relationship model
77. Improving ____ leads to more flexible queries.
a. denormalization
b. atomicity
c. normalization
d. derived attributes
78. If an entity’s existence depends on the existence of one or more other entities, it is said to be
_____-dependent.
a. existence
b. relationship
c. weak
d. business
79. At the implementation level, the supertype and its subtype(s) depicted in the specialization hierarchy maintain a ____ relationship.
a. none
b. 1:1
c. 1:M
d. M:N
80. ANSI-standard SQL allows the use of special operators in conjunction with the WHERE clause. A special operator used to check whether an attribute value matches a value contained within a subset of listed values is ____.
a. IS NULL
b. BETWEEN
c. IN
d. LIKE
Complete each statement.
81. From a data modeling point of view, time-variant data refer to data whose values change over time and for which you must keep a history of the data changes.
82. SQL has a basic vocabulary of fewer than 100 words.
83. Disjoint subtypes, also known as non-overlapping subtypes , are subtypes that contain a unique subset of the supertype entity set.
84. The primary key main function is to uniquely identify an entity instance or row within a table.
85. A(n) natural key or natural identifier is a real-world, generally accepted identifier used to distinguish that is, uniquely identify real-world objects.
86. The ER model refers to a specific table row as an entity instance.
87. Frequency distributions can be created quickly and easily using the SQL GROUP BY clause.
88. The specialization hierarchy depicts the arrangement of higher-level entity supertypes (parent entities) and lower-level entity subtypes (child entities).
89. A(n) domain is the attribute’s set of possible values.
90. To restore the values of a table, provided you have not used the COMMIT command, you must use the ROLLBACK command.
91. A relational table must not contain repeating groups.
92. Relationship strength depends on how the primary key of the related entity is formulated, while the relationship participation depends on how the business rule is written.
93. SQL allows the use of logical restrictions on its inquiries using OR, AND, and NOT.
94. Partial completeness means some supertype occurrences that are not members of any subtype.
95. In the relationship “EMPLOYEE claims DEPENDENT” the DEPENDENT entity is
existence-dependent on the EMPLOYEE entity.
96. An attribute representing one or more college degrees belonging to a person would be a(n)
multivalued attribute.
97. Primary keys are underlined in an ER diagram.
98. A(n) join is performed when data is retrieved from more than one table at a time.
99. Any changes made to the table contents are not physically saved on disk until you use the
COMMIT
