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Database Management > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

<p>Define relational database</p>

A

<p>enables logical representation of the data and its relationships
</p>

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2
Q

<p>what facilitates the creation of data relationships based on a logical construct?</p>

A

<p>Relation</p>

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3
Q

<p>Define table</p>

A

<p>two-dimensional structure composed of rows and columns</p>

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4
Q

<p>define key</p>

A

<p>one or more attributes that determine other attribute</p>

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5
Q

<p>What is the key's role based on?</p>

A

<p>determination</p>

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6
Q

<p>define functional dependence</p>

A

<p>attribute B is functionally dependent on A if all rows in table agree in value for A also agree in value for B</p>

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7
Q

<p>define primary key</p>

A

<p>Attribute or combination of attributes that uniquely identifies any given row
</p>

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8
Q

<p>composite key</p>

A

<p>Composed of more than one attribute

| </p>

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9
Q

<p>super key</p>

A

<p>Any key that uniquely identified each row

| </p>

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10
Q

<p>candidate key</p>

A

<p>A super key without unnecessary attributes

| </p>

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11
Q

<p>Entity integrity key</p>

A

<p>Each row (entity instance) in the table has its own unique identity
</p>

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12
Q

<p>Nulls</p>

A

<p>No data entry, Not permitted in primary key, &amp;amp; should be avoided in other attributes.
</p>

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13
Q

<p>Foreign Key</p>

A

<p>An attribute whose values match primary key values in the related table
</p>

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14
Q

<p>referential integrity</p>

A

<p>FK contains a “VALID” value that refers to an existing valid tuple (row) in another relation</p>

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15
Q

<p>T/F, many RDBM's do not enforce integrity rules automatically</p>

A

<p>F</p>

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16
Q

<p>inner join</p>

A

<p>only returns matched records from the tables that are being joined</p>

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17
Q

<p>natural join</p>

A

<p>links tables by selecting rows with common values in common attributes</p>

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18
Q

<p>Outer join</p>

A

<p>matched pairs are retained and any unmatched values in other table are left null</p>

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19
Q

<p>Data dictionary</p>

A

<p>Provides detailed accounting of all tables found within the user/designer-created database
Contains (at least) all the attribute names and characteristics for each table in the system
Contains metadata: data about data
</p>

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20
Q

<p>system catalog</p>

A

<p>Contains metadata
Detailed system data dictionary that describes all objects within the database
</p>

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21
Q

<p>homonym</p>

A

<p>Indicates the use of the same name to label different attributes
</p>

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22
Q

<p>synonym</p>

A

<p>Indicates the use of different names to describe the same attribute
</p>

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23
Q

<p>1:M</p>

A

<p>Relational modeling ideal
Should be the norm in any relational database design
</p>

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24
Q

<p>1:1</p>

A

<p>Should be rare in any relational database design

| </p>

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25
Q

<p>M:N relationships

| </p>

A

<p>Cannot be implemented as such in the relational model
Can be changed into 1:M relationships
</p>

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26
Q

<p>What does data redundancy lead to?</p>

A

<p>data anomalies</p>

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27
Q

<p>what functions do foreign keys play?</p>

A

<p>Control data redundancies by using common attributes shared by tables
Crucial to exercising data redundancy control
</p>

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28
Q

<p>Indexes</p>

A

<p>Orderly arrangement to logically access rows in a table

| </p>

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29
Q

<p>Index key</p>

A

<p>Index’s reference point
Points to data location identified by the key
</p>

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30
Q

<p>unique index</p>

A

<p>Index in which the index key can have only one pointer value (row) associated with it
</p>

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31
Q

<p>t/f, each index is associated with only one table</p>

A

<p>T</p>

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32
Q

<p>define entity</p>

A

<p>an entity is a single person, place, or thing about which data can be stored.</p>

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33
Q

<p>degrees</p>

A

<p>number of entities in a relationship</p>

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34
Q

<p>unary relationship</p>

A

<p>A unary relationship is when both participants in the relationship are the same entity.</p>

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35
Q

<p>binary relationship</p>

A

<p> two entities participate and is the most common relationship degree.</p>

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36
Q

<p>cardinality</p>

A

<p>refers to the uniqueness of data values contained in a particular column (attribute) of a database table.</p>

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37
Q

<p>attribute</p>

A

<p>may describe a component of the database, such as a table or a field, or may be used itself as another term for a field.</p>

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38
Q

<p>associative entity</p>

A

<p>associates the instances of more or more entity types and contains attributes that are specific to the relationship between those entity instances.</p>

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39
Q

<p>an entity is also called a blank</p>

A

<p>object</p>

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40
Q

<p>an object of interest to the end user</p>

A

<p>entity</p>

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41
Q

<p>characteristics of entities</p>

A

<p>attributes</p>

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42
Q

<p>attribute that must have value</p>

A

<p>required attribute

| </p>

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43
Q

<p>required attribute</p>

A

<p>attribute that must have value</p>

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44
Q

<p>attribute that does not require a value</p>

A

<p>optional attribute</p>

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45
Q

<p>optional attribute</p>

A

<p>attribute that does not require a value</p>

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46
Q

<p>attribute that does not require a value</p>

A

<p>optional attribute</p>

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47
Q

<p>set of possible values for a given attribute</p>

A

<p>domain</p>

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48
Q

<p>domain</p>

A

<p>set of possible attributes for a given domain</p>

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49
Q

<p>one or more attributes that uniquely identify each entity instance</p>

A

<p>identifiers (primary keys)</p>

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50
Q

<p>primary key composed of more than one attribute</p>

A

<p>composite key</p>

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51
Q

<p>an attribute that can be further subdivided to yield additional attributes</p>

A

<p>composite attribute</p>

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52
Q

<p>an attribute that cannot be subdivided</p>

A

<p>simple attribute</p>

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53
Q

<p>Address is an example of a what?</p>

A

<p>composite attribute</p>

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54
Q

<p>age is an example of what</p>

A

<p>simple attribute</p>

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55
Q

<p>attribute whose value is calculated from other attributes</p>

A

<p>derived attribute</p>

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56
Q

<p>entities that participate in a relationship</p>

A

<p>participants</p>

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57
Q

<p>describes relationship classification</p>

A

<p>connectivity</p>

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58
Q

<p>expresses the minimum and maximum number of entity occurrence associated with one occurrence of the related entity</p>

A

<p>cardinality</p>

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59
Q

<p>crows feet are a form of </p>

A

<p>cardinality</p>

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60
Q

<p>can exist in the database only when it is associated with another related entity occurence</p>

A

<p>existence dependent</p>

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61
Q

<p>an entity that can exist apart from all of its related entities</p>

A

<p>existence independent</p>

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62
Q

<p>existence independent is also referred to as </p>

A

<p>strong entity or regular entity</p>

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63
Q

<p>exists if the primary key of the related entity does not contain a primary component of the parent entity</p>

A

<p>weak relationship</p>

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64
Q

<p>when the primary key of the related entity contains a primary key component of the parent entity</p>

A

<p>strong relationship</p>

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65
Q

<p>number of entities or participants associated with a relationship</p>

A

<p>relationship degree</p>

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66
Q

<p>when an association is maintained within a single entity</p>

A

<p>unary</p>

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67
Q

<p>two entities are associated </p>

A

<p>binary</p>

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68
Q

<p>three entities are associated</p>

A

<p>ternary</p>

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69
Q

<p>an entity that cannot be uniquely identified by its attributes alone</p>

A

<p>weak entity</p>

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70
Q

<p>a bridge table is also called</p>

A

<p>associative entity</p>

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71
Q

<p>a joint table is also referred to as</p>

A

<p>associative entity or bridge table</p>

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72
Q

<p>An entity which has its own key attribute is a regular entity.</p>

A

<p>regular entity or strong entity</p>

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73
Q

<p>An entity which depends on other entity for its existence and doesn't have any key attribute of its own</p>

A

<p>weak entity</p>

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74
Q

<p>In a parent/child relationship, a parent is considered as a strong entity and the child is what kind of entity</p>

A

<p>weak entity</p>

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75
Q

<p>the age of a student is considered what kind of attribute?</p>

A

<p>single value attribute</p>

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76
Q

<p>the telephone number of an employee is considered what kind of attribute?</p>

A

<p>multi-valued attribute</p>

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77
Q

<p>An employee works for an organization. Here "works for" is a what?</p>

A

<p>relationship</p>

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78
Q

<p>define data</p>

A

<p>raw facts</p>

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79
Q

<p>define information</p>

A

<p>result of processing raw data</p>

80
Q

<p>result of processing raw data</p>

A

<p>information</p>

81
Q

<p>knowledge</p>

A

<p>the body of information and facts about a specific subject</p>

82
Q

<p>the body of information and facts about a specific subject</p>

A

<p>knowledge</p>

83
Q

<p>data management</p>

A

<p>focuses on the proper generation, storage, and retrieval of data</p>

84
Q

<p>focuses on the proper generation, storage, and retrieval of data</p>

A

<p>data management</p>

85
Q

<p>database</p>

A

<p>shared, integrated computer structure that stores a collection of end-user data and metadata</p>

86
Q

<p>shared, integrated computer structure that stores a collection of end-user data and metadata</p>

A

<p>database</p>

87
Q

<p>database management system</p>

A

<p>collection of programs that manages the database structure and controls access to data in database</p>

88
Q

<p>collection of programs that manages the database structure and controls access to data in database</p>

A

<p>database management system</p>

89
Q

<p>data inconsistency</p>

A

<p>different versions of the same data appear in different places</p>

90
Q

<p>different versions of the same data appear in different places</p>

A

<p>data inconcistency</p>

91
Q

<p>query</p>

A

<p>specific request issued to the DBMS </p>

92
Q

<p>ad hoc query</p>

A

<p>spur of the moment question</p>

93
Q

<p>spur of the moment question</p>

A

<p>ad hoc query</p>

94
Q

<p>data quality</p>

A

<p>approach to promoting the accuracy, validity, and timeliness of data</p>

95
Q

<p>approach to promoting the accuracy, validity, and timeliness of data</p>

A

<p>data quality</p>

96
Q

<p>single-user database</p>

A

<p>supports only one use at a time</p>

97
Q

<p>supports only one use at a time</p>

A

<p>single-user database</p>

98
Q

<p>what is another word for single-user database?</p>

A

<p>desktop database</p>

99
Q

<p>multiuser database</p>

A

<p>supports multiple users at the same time</p>

100
Q

<p>supports multiple users at the same time</p>

A

<p>multiuser database</p>

101
Q

<p>multiuser database is also called</p>

A

<p>workgroup database</p>

102
Q

<p>enterprise database</p>

A

<p>used for an organization or more than 50 users</p>

103
Q

<p>used for an organization or more than 50 users</p>

A

<p>enterprise database</p>

104
Q

<p>centralized database</p>

A

<p>supports data located at a single site</p>

105
Q

<p>supports data located at a single site</p>

A

<p>centralized database</p>

106
Q

<p>distributed database</p>

A

<p>supports data distributed across several sites</p>

107
Q

<p>supports data distributed across several sites</p>

A

<p>distributed database</p>

108
Q

<p>operational database</p>

A

<p>support a company's day to day operations</p>

109
Q

<p>support a company's day to day operations</p>

A

<p>operational database</p>

110
Q

<p>operational databases are also referred to as</p>

A

<p>production database</p>

111
Q

<p>analytical database</p>

A

<p>stores historical data and business metrics used for tactical or strategic decision making</p>

112
Q

<p>stores historical data and business metrics used for tactical or strategic decision making</p>

A

<p>analytical database</p>

113
Q

<p>data warehouse</p>

A

<p>stores data in a format optimized for decision support</p>

114
Q

<p>online analytical processing</p>

A

<p>set of tools that work together to provide an advanced data analysis environment for retrieving, processing and modeling data</p>

115
Q

<p>set of tools that work together to provide an advanced data analysis environment for retrieving, processing and modeling data</p>

A

<p>online analytical processing</p>

116
Q

<p>business intelligence</p>

A

<p>comprehensive approach to capture and process business data with the purpose of generating info to support decision making</p>

117
Q

<p>comprehensive approach to capture and process business data with the purpose of generating info to support decision making</p>

A

<p>business intelligence</p>

118
Q

<p>Unstructured data</p>

A

<p>data that exist in their raw state</p>

119
Q

<p>data that exist in their raw state</p>

A

<p>Unstructured data</p>

120
Q

<p>structured data</p>

A

<p>result of formatting unstructured data to facilitate storage, use, and generation of info</p>

121
Q

<p>result of formatting unstructured data to facilitate storage, use, and generation of info</p>

A

<p>structured data</p>

122
Q

<p>Semistructured data</p>

A

<p>partly processed data</p>

123
Q

<p>Extensible Markup Language (XML)</p>

A

<p>language used to represent and manipulate data elements in a text format</p>

124
Q

<p>language used to represent and manipulate data elements in a text format</p>

A

<p>Extensible Markup Language (XML)</p>

125
Q

<p>extended entity relationship model (EERM)</p>

A

<p>results from adding more semantic constructs to the original ER model</p>

126
Q

<p>results from adding more semantic constructs to the original ER model</p>

A

<p>extended entity relationship model (EERM)</p>

127
Q

<p>entity supertype</p>

A

<p>generic entity type that is related to one or more entity subtypes</p>

128
Q

<p>generic entity type that is related to one or more entity subtypes</p>

A

<p>entity subtype</p>

129
Q

<p>specialization hierarchy</p>

A

<p>depicts the arrangement of higher-level entity supertypes</p>

130
Q

<p>enables an entity subtype to inherit the attributes and relationships of the supertype</p>

A

<p>inheritance</p>

131
Q

<p>attribute that determines to which subtype the supertype is related</p>

A

<p>subtype discriminator</p>

132
Q

<p>Subtypes that contain a unique subset of the supertype entity set </p>

A

<p>disjoint types</p>

133
Q

<p>specifies whether each entity supertype occurence must also be a member of at least one subtype</p>

A

<p>completeness constraint</p>

134
Q

<p>virtual entity type used to represent multiple entities into a single, abstract entity object</p>

A

<p>entity cluster</p>

135
Q

<p>real-world, generally accepted identifier that uniquely identifies real-world objects</p>

A

<p>natural key (natural identifier)</p>

136
Q

<p>when a relationship is improperly or incompletely identified </p>

A

<p>design trap</p>

137
Q

<p>one entity in two 1:M relationships to other entities</p>

A

<p>fan trap</p>

138
Q

<p>gives logical structure to a database graphically</p>

A

<p>entity relationship diagram</p>

139
Q

<p>Lengthy development times, difficulty getting quick answers, complex system administration, lack of security and data sharing and extensive programming are examples of what?</p>

A

<p>problems with the traditional file system</p>

140
Q

A relational database consists of a collection of

A

Tables

141
Q

A ________ in a table represents a relationship among a set of values.

A

a) Column
b) Key
c) Row
d) Entry
Answer :C

142
Q

The term _______ is used to refer to a row.

A

tuple

143
Q

For each attribute of a relation, there is a set of permitted values, called the ________ of that attribute.

A

domain

144
Q

Database __________ , which is the logical design of the database, and the database _______,which is a snapshot of the data in the database at a given instant in time.

A

schema, instance

145
Q

The tuples of the relations can be of ________ order.

A

any

146
Q
  1. Which one of the following is a set of one or more attributes taken collectively to uniquely identify a record?
    a) Candidate key
    b) Sub key
    c) Super key
    d) Foreign key
A

Superkey

147
Q
  1. Consider attributes ID , CITY and NAME . Which one of this can be considered as a super key ?
    a) NAME
    b) ID
    c) CITY
    d) CITY , ID
A

Answer:b
Explanation:Here the id is the only attribute which can be taken as a key. Other attributes are not uniquely identified .

148
Q
  1. The subset of super key is a candidate key under what condition ?
    a) No proper subset is a super key
    b) All subsets are super keys
    c) Subset is a super key
    d) Each subset is a super key
A

Answer:a
Explanation:The subset of a set cannot be the same set.Candidate key is a set from a super key which cannot be the whole of the super set

149
Q
  1. A _____ is a property of the entire relation, rather than of the individual tuples in which each tuple is unique.
    a) Rows
    b) Key
    c) Attribute
    d) Fields
A

Answer:b
Explanation:Key is the constraint which specifies uniqueness.

150
Q
  1. Which one of the following attribute can be taken as a primary key ?
    a) Name
    b) Street
    c) Id
    d) Department
A

Answer:c
Explanation:The attributes name , street and department can repeat for some tuples.But the id attribute has to be unique .So it forms a primary key.

151
Q
  1. Which one of the following cannot be taken as a primary key ?
    a) Id
    b) Register number
    c) Dept_id
    d) Street
A

Answer:d
Explanation:Street is the only attribute which can occur more than once

152
Q
  1. A attribute in a relation is a foreign key if the _______ key from one relation is used as an attribute in that relation .
    a) Candidate
    b) Primary
    c) Super
    d) Sub
A

Answer:b
Explanation:The primary key has to be referred in the other relation to form a foreign key in that relation .

153
Q
  1. The relation with the attribute which is the primary key is referenced in another relation. The relation which has the attribute as primary key is called
    a) Referential relation
    b) Referencing relation
    c) Referenced relation
    d) Referred relation
A

Answer:b
Explanation:None.

154
Q
  1. A _________ integrity constraint requires that the values appearing in specified attributes of any tuple in the referencing relation also appear in specified attributes of at least one tuple in the referenced relation.
    a) Referential
    b) Referencing
    c) Specific
    d) Primary
A

Answer:a
Explanation:A relation, say r1, may include among its attributes the primary key of another relation, say r2. This attribute is called a foreign key from r1, referencing r2. The relation r1 is also called the referencing relation of the foreign key dependency, and r2 is called the referenced relation of the foreign key.

155
Q
  1. What is the purpose of index in sql server
    a) To enhance the query performance
    b) To provide an index to a record
    c) To perform fast searches
    d) All of the mentioned
A

Answer: d
Explanation: A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes.

156
Q
  1. What is true about indexes?
    a) Indexes enhance the performance even if the table is updated frequently
    b) It makes harder for sql server engines to work to work on index which have large keys
    c) It doesn’t make harder for sql server engines to work to work on index which have large keys
    d) None of the mentioned
A

Answer: b
Explanation: Indexes tend to improve the performance.

157
Q
  1. Does index take space in the disk ?
    a) It stores memory as and when required
    b) Yes, Indexes are stored on disk
    c) Indexes are never stored on disk
    d) Indexes take no space
A

Answer: b
Explanation: Indexes take memory slots which are located on the disk.

158
Q
  1. What are composite indexes ?
    a) Are those which are composed by database for its internal use
    b) A composite index is a combination of index on 2 or more columns
    c) Composite index can never be created
    d) None of the mentioned
A

Answer: b
Explanation: A composite index is an index on two or more columns of a table.

159
Q
  1. If an index is _________________ the metadata and statistics continue to exists
    a) Disabling
    b) Dropping
    c) Altering
    d) Both a and b
A

Answer: a
Explanation: A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes.

160
Q
  1. Using which language can a user request information from a database ?
    a) Query
    b) Relational
    c) Structural
    d) Compiler
A

a

161
Q
  1. Student(ID, name, dept name, tot_cred)
    In this query which attribute form the primary key?
    a) Name
    b) Dept
    c) Tot_cred
    d) ID
A

Answer:d
Explanation:The attributes name ,dept and tot_cred can have same values unlike ID .

162
Q
  1. The_____ operation allows the combining of two relations by merging pairs of tuples, one from each relation, into a single tuple.
    a) Select
    b) Join
    c) Union
    d) Intersection
A

Answer:b
Explanation:Join finds the common tuple in the relations and combines it.

163
Q

a) Union
b) Join
c) Product
d) Intersect

A

Answer:a
Explanation:Union just combines all the values of relations of same attributes.

164
Q
  1. The _______ operator takes the results of two queries and returns only rows that appear in both result sets.
    a) Union
    b) Intersect
    c) Difference
    d) Projection
A

Answer:b
Explanation:The union operator gives the result which is the union of two queries and difference is the one where query which is not a part of second query

165
Q
  1. The basic data type char(n) is a _____ length character string and varchar(n) is _____ length character.
    a) Fixed, equal
    b) Equal, variable
    c) Fixed, variable
    d) Variable, equal
A

Answer:c
Explanation: Varchar changes its length accordingly whereas char has a specific length which has to be filled by either letters or spaces .

166
Q
  1. To remove a relation from an SQL database, we use the ______ command.
    a) Delete
    b) Purge
    c) Remove
    d) Drop table
A

d

167
Q 
1.
Name
Annie
Bob
Callie
Derek
Which of these query will display the the table given above ?
a) Select employee from name
b) Select name
c) Select name from employee
d) Select employee
A

Answer:c
Explanation:The field to be displayed is included in select and the table is included in the from clause.

168
Q 
2. Select \_\_\_\_\_\_\_\_ dept_name
from instructor;
Here which of the following displays the unique values of the column ?
a) All
b) From
c) Distinct
d) Name
A

Answer:c
Explanation:Distinct keyword selects only the entries that are unique.

169
Q
  1. The ______ clause allows us to select only those rows in the result relation of the ____ clause that satisfy a specified predicate.
    a) Where, from
    b) From, select
    c) Select, from
    d) From, where
A

a

170
Q
  1. The ________ clause is used to list the attributes desired in the result of a query.
    a) Where
    b) Select
    c) From
    d) Distinct
A

b

171
Q
  1. Select * from employee where salary>10000 and dept_id=101;
    Which of the following fields are displayed as output?
    a) Salary, dept_id
    b) Employee
    c) Salary
    d) All the field of employee relation
A

Answer:d
Explanation:Here * is used to select all the fields of the relation .

172
Q
  1. Which of the following statements contains an error?
    A) Select * from emp where empid = 10003;
    B) Select empid from emp where empid = 10006;
    C) Select empid from emp;
    D) Select empid where empid = 1009 and lastname = ‘GELLER’;
A

Explanation:This query do not have from clause which specifies the relation from which the values has to be selected .

173
Q
  1. Which of the join operations do not preserve non matched tuples.
    a) Left outer join
    b) Right outer join
    c) Inner join
    d) Natural join
A

Answer:c
Explanation:INNER JOIN: Returns all rows when there is at least one match in BOTH tables.

174
Q
  1. What type of join is needed when you wish to include rows that do not have matching values?
    a) Equi-join
    b) Natural join
    c) Outer join
    d) All of the mentioned
A

Answer:c
Explanation:An outer join does not require each record in the two joined tables to have a matching record..

175
Q
  1. How many tables may be included with a join?
    a) One
    b) Two
    c) Three
    d) All of the mentioned
A

Answer:d
Explanation:Join can combine multiple tables

176
Q
  1. Which join refers to join records from the right table that have no matching key in the left table are include in the result set:
    a) Left outer join
    b) Right outer join
    c) Full outer join
    d) Half outer join
A

Answer:b
Explanation:RIGHT OUTER JOIN: Return all rows from the right table, and the matched rows from the left table.

177
Q
  1. An ________ is a set of entities of the same type that share the same properties, or attributes .
    a) Entity set
    b) Attribute set
    c) Relation set
    d) Entity model
A

Answer:a
Explanation:An entity is a “thing” or “object” in the real world that is distinguishable from all other objects.

178
Q
  1. Entity is a
    a) Object of relation
    b) Present working model
    c) Thing in real world
    d) Model of relation
A

Answer:c
Explanation:For example, each person in a university is an entity.

179
Q
  1. The descriptive property possessed by each entity set is _________ .
    a) Entity
    b) Attribute
    c) Relation
    d) Model
A

b

180
Q
  1. The function that an entity plays in a relationship is called that entity’s _____________.
    a) Participation
    b) Position
    c) Role
    d) Instance
A

Answer:c
Explanation:A relationship is an association among several entities.

181
Q
  1. The attribute name could be structured as a attribute consisting of first name, middle initial, and last name . This type of attribute is called
    a) Simple attribute
    b) Composite attribute
    c) Multivalued attribute
    d) Derived attribute
A

Answer:b
Explanation:Composite attributes can be divided into subparts (that is, other attributes).

182
Q
  1. The attribute AGE is calculated from DATE_OF_BIRTH . The attribute AGE is
    a) Single valued
    b) Multi valued
    c) Composite
    d) Derived
A

Answer:d
Explanation:The value for this type of attribute can be derived from the values of other related attributes or entities.

183
Q
  1. Not applicable condition can be represented in relation entry as
    a) NA
    b) 0
    c) NULL
    d) Blank Space
A

c

184
Q
  1. Which of the following can be a multivalued attribute ?
    a) Phone_number
    b) Name
    c) Date_of_birth
    d) All of the mentioned
A

Answer:a
Explanation:Name and Date_of_birth cannot hold more than 1 value.

185
Q
  1. Which of the following is a single valued attribute
    a) Register_number
    b) Address
    c) SUBJECT_TAKEN
    d) Reference
A

a

186
Q
  1. In a relation between the entities the type and condition of the relation should be specified . That is called as______attribute
    a) Desciptive
    b) Derived
    c) Recursive
    d) Relative
A

Answer:a
Explanation:Consider the entity sets student and section, which participate in a relationship set takes. We may wish to store a descriptive attribute grade with the relationship to record the grade that a student got in the class.

187
Q

define generalization

A

process of defining a more general supertype from a set of more specialized entity types

188
Q

define specialization

A

process of defining one or more subtypes from a general supertype; top down process

189
Q

how is a total specialization rule indicated?

A

double line

190
Q

how is an incomplete specialization rule indicated?

A

single line

191
Q

disjointness constraint

A

whether an instance of a supertype may simultaneously be a member of two or more subtypes

192
Q

disjoint rule

A
  • No letter “d”

- An instance of a supertype can be only one of the subtypes

193
Q

Overlap rule

A
  • Yes letter “o”

- an instance of a supertype can simultaneously be a member of two or more subtypes

194
Q

Is this statement an example of the overlap rule or the disjoint rule? A patient can either be an outpatient or a resident but not both at any given time.

A

disjoint rule

This will be indicated by a letter “d” in the diagram

195
Q

Is this statement an example of the overlap rule or the disjoint rule? A part may both manufactured and purchased.

A

Overlap rule

This will be indicated by a letter “o” in the diagram

196
Q

define subtype discriminator

A

a mechanism to implement supertype/subtype relationships

197
Q

Foreign is always on what side of the relationship?

A

on the many side

Database Management (4 decks)

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