Download Chapter 7: Managing Data Resources

Chapter 7
Managing Data Resources
7-1
Chapter 7
Managing Data Resources
True-False Questions
1.
Most organizations have inefficient information systems because of poor hardware and
software.
Answer: False
2.
p. 230
Difficulty:
Easy
Reference:
p. 230
Difficulty:
Easy
Reference:
p. 230
Difficulty:
Easy
Reference:
p. 231
Difficulty:
Easy
Reference:
p. 232
Difficulty:
Easy
Reference:
p. 232
A traditional file system normally does not have difficulty with ad hoc reports if there is a
programmer available who can write the data query.
Answer: False
9.
Reference:
In a traditional file environment, any change in data requires a change in all programs that
access the data.
Answer: True
8.
Easy
Every traditional computer program has to describe the location and nature of the data with
which it works.
Answer: False
7.
Difficulty:
In most organizations, systems tend to grow independently and not according to a plan.
Answer: True
6.
p. 230
Every record in a file should contain at least one key field.
Answer: True
5.
Reference:
Each characteristic or quality describing a particular entity is called an attribute.
Answer: True
4.
Easy
A grouping of characters into a word, a group of words, or a complete number is called a
record.
Answer: False
3.
Difficulty:
Difficulty:
Hard
Reference:
p. 233
Reference:
p. 233
DBMS separate the logical and physical views of the data.
Answer: True
Difficulty:
Medium
7-2
Managing Data Resources
10.
The data definition language defines each data element as it appears in the database after that
data element is translated into the forms required by application programs.
Answer: False
11.
Difficulty:
Medium
Reference:
p. 239
Difficulty:
Medium
Reference:
p. 239
Difficulty:
Easy
Reference:
p. 239
Difficulty:
Medium
Reference:
p. 239
Difficulty:
Medium
Reference:
p. 239
Difficulty:
Easy
Reference:
p. 240
Difficulty:
Easy
Reference:
p. 240
Many applications today require databases that can store and retrieve multimedia.
Answer: True
20.
p. 236
Many large legacy systems requiring intensive high-volume transaction processing use
hierarchical DBMS.
Answer: True
19.
Reference:
Network database management systems are no longer used for building new database
applications.
Answer: True
18.
Hard
The top-level segment in each record of a hierarchical database is called the root.
Answer: True
17.
Difficulty:
In a hierarchical DBMS, a parent can have only one child.
Answer: False
16.
p. 234
In a hierarchical DBMS, an upper segment is connected logically to a lower segment in a
parent-child relationship.
Answer: True
15.
Reference:
In a hierarchical DBMS, data elements within each record are organized into pieces called
segments.
Answer: True
14.
Hard
Hierarchical structures support many-to-many relationships among entities.
Answer: False
13.
Difficulty:
The strength of the relational model is that data in any file or table can be related to another
file or table as long as both tables share a common key field.
Answer: False
12.
Chapter 7
Difficulty:
Easy
Reference:
p. 240
Medium
Reference:
p. 240
OODBMS cannot work with applets.
Answer: False
Difficulty:
Chapter 7
21.
Managing Data Resources
In the future, database design will have to consider how the organization can share some of
its data with its business partners.
Answer: True
22.
Difficulty:
Easy
Reference:
p. 241
Difficulty:
Medium
Reference:
p. 242
Difficulty:
Medium
Reference:
p. 242
Difficulty:
Medium
Reference:
p. 243
Difficulty:
Easy
Reference:
p. 243
Difficulty:
Hard
Reference:
p. 244
Difficulty:
Medium
Reference:
p. 244
“Slice and dice” is the main technique for multidimensional reporting.
Answer: True
31.
p. 240
Today, what has been immediately available at most firms is historical data only.
Answer: False
30.
Reference:
Multidimensional modeling is the analysis of large pools of data to find patterns and rules
that can be used to guide decision making and predict future behavior.
Answer: False
29.
Medium
Distributed systems reduce the vulnerability of a single central site.
Answer: True
28.
Difficulty:
Local databases can pose security problems by widely distributing access to sensitive data.
Answer: True
27.
p. 240
In a partitioned database, parts of the database are stored and maintained physically in one
location and other parts are stored and maintained in other locations.
Answer: True
26.
Reference:
In an entity-relationship diagram, a line connecting two entities that ends in two short marks
designates a many-to-many relationship.
Answer: False
25.
Easy
In a relational database, complex groupings of data must be streamlined to eliminate
awkward many-to-many relationships.
Answer: True
24.
Difficulty:
OODBMS are slower than relational DBMS.
Answer: True
23.
7-3
Difficulty:
Hard
Reference:
p. 245
Reference:
p. 245
A data warehouse may include a legacy system.
Answer: True
Difficulty:
Easy
7-4
Managing Data Resources
32.
A data warehouse is a small data mart.
Answer: False
33.
Reference:
p. 246
Difficulty:
Easy
Reference:
p. 248
Difficulty:
Easy
Reference:
p. 249
Difficulty:
Medium
Reference:
p. 249
Difficulty:
Easy
Reference:
p. 250
Difficulty:
Easy
Reference:
p. 251
A firm’s information policy lays out who is responsible for updating and maintaining the
information in a database system.
Answer: True
40.
Easy
Data administration is a very important organizational function, and is fairly easy to
implement.
Answer: False
39.
Difficulty:
A database requires organizational and conceptual change.
Answer: True
38.
p. 245
Common Gateway Interface is a specification for transferring information between a Web
server and a program designed to accept and return data.
Answer: True
37.
Reference:
A Web interface requires changes to the internal database.
Answer: False
36.
Easy
Middleware is used to transfer information from the organization’s internal database back to
the Web server for delivering the form of a Web page to the inquirer.
Answer: True
35.
Difficulty:
Data mining can be a challenge to individual privacy.
Answer: True
34.
Chapter 7
Difficulty:
Easy
Reference:
pp. 251-252
A traditional system serves a wider community of users than a database because less training
is involved.
Answer: False
Difficulty:
Medium
Reference:
p. 252
Chapter 7
Managing Data Resources
7-5
Multiple-Choice Questions
41.
A characteristic or quality describing an entity is called a(n):
a.
b.
c.
d.
field.
tuple.
key field.
attribute.
Answer:
42.
Reference:
p. 230
c
Difficulty:
Easy
Reference:
p. 230
Easy
Reference:
p. 232
Reference:
p. 232
Duplicate data in multiple data files is:
a.
b.
c.
d.
data redundancy.
data multiplication.
data independence.
typical of a relational model.
Answer:
a
Difficulty:
In a traditional file environment, any change in data requires:
a.
b.
c.
d.
a different entity description.
a change in all programs that access the data.
a different data dictionary.
management approval.
Answer:
45.
Easy
entities, attributes, fields, and records.
fields, attributes, entities, and records.
fields, records, files, and databases.
records, entities, fields, and databases.
Answer:
44.
Difficulty:
The data hierarchy goes from bits and bytes to:
a.
b.
c.
d.
43.
d
b
Difficulty:
Medium
The confusion created by __________________ makes it difficult for companies to
create customer relationship management, supply chain management, or enterprise
systems that integrate data from different sources.
a.
b.
c.
d.
batch processing
data redundancy
data independence
online processing
Answer:
b
Difficulty:
Easy
Reference:
p. 232
7-6
Managing Data Resources
46.
The DBMS acts as an interface between _______________ and the _______________.
a.
b.
c.
d.
application programs; physical data files
data dictionary; batch processor
user’s view; data manipulation language
data definition language; logical view
Answer:
47.
Easy
Reference:
p. 233
d
Difficulty:
Medium
Reference:
p. 233
The logical description of the entire database showing all the data elements and
relationships among them best describes:
a.
b.
c.
d.
data dictionary.
conceptual schema.
subschema.
data definition language.
Answer:
b
Difficulty:
Medium
Reference:
p. 233
The formal language programmers use to specify the content and structure of the
database is the:
a.
b.
c.
d.
data dictionary language.
data manipulation language.
Structured Query Language.
data definition language.
Answer:
50.
Difficulty:
shows how data are organized and structured on the storage media.
presents an entry screen to the user.
allows the creation of supplementary reports.
presents data as they would be perceived by end users.
Answer:
49.
a
The logical view:
a.
b.
c.
d.
48.
Chapter 7
d
Difficulty:
Medium
Reference:
p. 234
Reference:
p. 234
The most prominent data manipulation language today is:
a.
b.
c.
d.
COBOL.
Fortran.
SQL.
Pascal.
Answer:
c
Difficulty:
Medium
Chapter 7
51.
Managing Data Resources
The data dictionary serves as an important data management tool by:
a.
b.
c.
d.
assigning attributes to the data.
creating an inventory of data contained in the database.
presenting data as end users or business specialists would perceive them.
maintaining data in updated form.
Answer:
52.
b
Difficulty:
Medium
Reference:
p. 234
The automated or manual file that stores information about data elements and data
characteristics such as usage, physical representation, ownership, authorization, and
security is the:
a.
b.
c.
d.
data dictionary.
logical view.
physical file.
relational file.
Answer:
53.
7-7
a
Difficulty:
Medium
Reference:
p. 234
The type of logical database model that treats data as if they were stored in twodimensional tables is the:
a. hierarchical DBMS.
b. hybrid DBMS.
c. relational DBMS.
d. network DBMS.
Answer:
54.
Difficulty:
Easy
Reference:
p. 236
Reference:
p. 236
In a relational database, a record is called a:
a.
b.
c.
d.
tuple.
row.
column.
table.
Answer:
55.
c
a
Difficulty:
Medium
In a relational database, the three basic operations used to develop useful sets of data are:
a.
b.
c.
d.
select, project, and where.
select, join, and where.
select, project, and join.
select, from, and join.
Answer:
c
Difficulty:
Medium
Reference:
p. 236
7-8
Managing Data Resources
56.
Chapter 7
The select operation:
a. combines relational tables to provide the user with more information than is
otherwise available.
b. creates a subset consisting of columns in a table.
c. identifies the table from which the columns will be selected.
d. creates a subset consisting of all records in the file that meets stated criteria.
Answer:
57.
d
Difficulty:
Easy
Reference:
p. 236
The join operation:
a. combines relational tables to provide the user with more information than is
otherwise available.
b. identifies the table from which the columns will be selected.
c. creates a subset consisting of columns in a table.
d. organizes elements into segments.
Answer:
58.
a
Difficulty:
Easy
Reference:
p. 236
The project operation:
a. combines relational tables to provide the user with more information than is
otherwise available.
b. creates a subset consisting of columns in a table.
c. organizes elements into segments.
d. identifies the table from which the columns will be selected.
Answer:
59.
Difficulty:
Easy
Reference:
p. 236
DBMS for midrange computers include all of the following EXCEPT:
a.
b.
c.
d.
DB2.
Oracle.
Microsoft SQL Server.
Microsoft Access.
Answer:
60.
b
d
Difficulty:
Medium
Reference:
p. 239
Reference:
p. 239
Oracle Lite is a(n):
a.
b.
c.
d.
DBMS for small handheld computing devices.
Internet DBMS.
mainframe relational DBMS.
DBMS for midrange computers.
Answer:
a
Difficulty:
Medium
Chapter 7
61.
Managing Data Resources
Access is a:
a.
b.
c.
d.
DBMS for small handheld computing devices.
mainframe relational DBMS.
DBMS for midrange computers.
PC relational DBMS.
Answer:
62.
Medium
Reference:
p. 239
c
Difficulty:
Medium
Reference:
p. 239
Reference:
p. 239
Microsoft SQL Server is a(n):
a.
b.
c.
d.
DBMS for small handheld computing devices.
Internet DBMS.
mainframe relational DBMS.
DBMS for midrange computers.
Answer:
d
Difficulty:
Medium
The older logical database model that is useful for depicting many-to-many relationships
is the:
a.
b.
c.
d.
hierarchical DBMS.
relational DBMS.
network DBMS.
object-oriented DBMS.
Answer:
65.
Difficulty:
DBMS for small handheld computing devices.
Internet DBMS.
mainframe relational DBMS.
DBMS for midrange computers.
Answer:
64.
d
IBM’s DB2 is a(n):
a.
b.
c.
d.
63.
7-9
c
Difficulty:
Easy
Reference:
p. 239
_______________________ systems can be slowed down if they require many accesses
to the data stored on the disk to carry out the select, join, and project commands.
a.
b.
c.
d.
Hierarchical
Relational
Object-oriented
Network
Answer:
b
Difficulty:
Easy
Reference:
p. 240
7-10
Managing Data Resources
66.
Banks, insurance companies, and other high-volume users continue to use reliable
hierarchical DBMS such as:
a.
b.
c.
d.
IBM’s IMS.
Microsoft Access.
DB2.
Oracle.
Answer:
67.
Hard
Reference:
p. 240
d
Difficulty:
Easy
Reference:
p. 240
For storing data types such as complex information or recursive data, _______________
are useful.
a.
b.
c.
d.
relational DBMS
hierarchical DBMS
network DBMS
OODBMS
Answer:
d
Difficulty:
Medium
Reference:
p. 240
Using object-oriented extensions to existing relational DBMS is one way to create a(n):
a.
b.
c.
d.
system of easily accessible reports.
Internet warehouse.
data mart.
hybrid DBMS.
Answer:
70.
Difficulty:
hierarchical DBMS.
relational DBMS.
network DBMS.
object-oriented DBMS.
Answer:
69.
a
The type of database management approach that can handle multimedia is the:
a.
b.
c.
d.
68.
Chapter 7
d
Difficulty:
Easy
Reference:
p. 240
The conceptual design of the database shows the database from a(n):
a.
b.
c.
d.
business perspective.
direct access perspective.
program perspective.
object-oriented perspective.
Answer:
a
Difficulty:
Easy
Reference:
p. 241
Chapter 7
71.
Managing Data Resources
Database designers document their data model with a(n):
a.
b.
c.
d.
entity-relationship diagram.
object-oriented diagram.
applet-diagram.
cube-diagram.
Answer:
72.
Easy
Reference:
p. 242
d
Difficulty:
Easy
Reference:
p. 242
Activities for detecting and correcting data in a database or file that are incorrect,
incomplete, improperly formatted, or redundant are called:
a.
b.
c.
d.
data auditing.
data fragmentating.
data cleansing.
data verifying.
Answer:
c
Difficulty:
Easy
Reference:
p. 244
The tool that enables users to view the same data in different ways using multiple
dimensions is:
a.
b.
c.
d.
object-oriented processing.
a relational database.
OLAP.
a data warehouse.
Answer:
75.
Difficulty:
contiguous
fragmented
split
partitioned
Answer:
74.
a
In a _______________ database, parts of the database are stored and maintained
physically in one location and other parts are stored and maintained in other locations.
a.
b.
c.
d.
73.
7-11
c
Difficulty:
Hard
Reference:
p. 244
Reference:
p. 245
A data warehouse is composed of:
a.
b.
c.
d.
historical data and an information directory.
OLAP and external data.
internal and external data sources.
marketing and sales.
Answer:
c
Difficulty:
Medium
7-12
Managing Data Resources
76.
The main technique for multidimensional reporting is:
a.
b.
c.
d.
SQL.
multiple relationships in large quantities of data.
OLAP.
data mining.
Answer:
77.
Easy
Reference:
p. 245
a
Difficulty:
Easy
Reference:
p. 246
Reference:
p. 248
One advantage to a hypermedia database is that:
a.
b.
c.
d.
it is always stored on the Internet.
the nodes can be accessed in any order.
it is written in HTML.
it is much more easily understood by outside users.
Answer:
b
Difficulty:
Medium
The popular specification for transferring information between a Web server and a
program designed to accept and return data is:
a.
b.
c.
d.
CGI.
HTML.
Java.
SQL.
Answer:
80.
Difficulty:
a data mart typically focuses on a single subject area or line of business.
all the information is historical.
a data mart is usually maintained completely at the Web site of the organization.
all of the information belongs to a single company.
Answer:
79.
c
A data mart usually can be constructed more rapidly and at lower cost than a data
warehouse because:
a.
b.
c.
d.
78.
Chapter 7
a
Difficulty:
Easy
Reference:
p. 249
The fundamental principle of data administration is that all data:
a.
b.
c.
d.
be normalized.
be owned by individual departments.
are recursive.
belongs to the company as a whole.
Answer:
d
Difficulty:
Medium
Reference:
p. 251
Chapter 7
Managing Data Resources
7-13
Fill in the Blanks
81.
A(n) computer system organizes data in a hierarchy that progresses from bits and bytes to
databases.
Difficulty: Medium
82.
Reference:
p. 230
Reference:
p. 230
Reference:
p. 230
Reference:
p. 230
The traditional file environment refers to a way of collecting and maintaining data in an
organization that leads to each functional area or division creating and maintaining its own
data files and programs.
Difficulty: Easy
90.
p. 230
A(n) key field is a field in a record that uniquely identifies instances of that record so that it
can be retrieved, updated, or sorted.
Difficulty: Easy
89.
Reference:
A(n) attribute is a piece of information describing a particular entity.
Difficulty: Easy
88.
p. 230
A(n) entity is a person, place, thing, or event about which information must be kept.
Difficulty: Easy
87.
Reference:
A(n) database is a group of related files.
Difficulty: Easy
86.
p. 230
A(n) file a group of records of the same type.
Difficulty: Easy
85.
Reference:
A(n) record is a group of related fields.
Difficulty: Easy
84.
p. 230
A(n) field is a grouping of characters into a word, a group of words, or a complete number,
such as a person’s name or age.
Difficulty: Easy
83.
Reference:
Reference:
p. 231
Data redundancy is the presence of duplicate data in multiple data files.
Difficulty: Medium
Reference:
p. 232
7-14
Managing Data Resources
91.
Program-data dependence is the close relationship between data stored in files and the
software programs that update and maintain those files.
Difficulty: Medium
92.
Reference:
p. 233
Reference:
p. 233
Reference:
p. 234
Reference:
p. 234
A(n) data manipulation language is a language associated with a database management
system that end users and programmers use to manipulate data in the database.
Difficulty: Easy
99.
p. 233
A(n) data definition language is that component of a database management system that
defines each data element as it appears in the database.
Difficulty: Medium
98.
Reference:
A subschema is the specific set of data from the database that is required by each user or
application program.
Difficulty: Medium
97.
p. 233
The physical view is the representation of data as they would actually be organized on
physical storage media.
Difficulty: Easy
96.
Reference:
The logical view is the representation of data as they would appear to an application
programmer or end user.
Difficulty: Easy
95.
p. 232
A(n) database management system is special software to create and maintain a database and
enable individual business applications to extract the data needed without having to create
separate files or data definitions in their computer programs.
Difficulty: Easy
94.
Reference:
A(n) database, by the most rigorous definition, is a collection of data organized to service
many applications at the same time by storing and managing data so that they appear to be in
one location.
Difficulty: Medium
93.
Chapter 7
Reference:
p. 234
Structured Query Language (SQL) is the standard data manipulation language for relational
database management systems.
Difficulty: Easy
Reference:
p. 234
Chapter 7
Managing Data Resources
7-15
100. A(n) data dictionary is an automated or manual tool for storing and organizing information
about the data maintained in a database.
Difficulty: Easy
Reference:
p. 234
101. Data dictionaries that simply report are called passive data dictionaries.
Difficulty: Medium
Reference:
p. 235
102. A(n) relational DBMS is a type of logical database model that treats data as if they were
stored in two-dimensional tables.
Difficulty: Easy
Reference:
p. 236
103. The join operation combines relational tables to provide the user with more information than
is available in individual tables.
Difficulty: Medium
Reference:
p. 236
104. A(n) tuple is a row or record in a relational database.
Difficulty: Easy
Reference:
p. 236
105. A(n) hierarchical DBMS is an older logical database model that organizes data into a
treelike structure.
Difficulty: Easy
Reference:
p. 239
106. A(n) networked DBMS is an older logical database model that is useful for depicting manyto-many relationships.
Difficulty: Easy
Reference:
p. 239
107. Network database management systems depict data logically as many-to-many relationships.
Difficulty: Easy
Reference:
p. 239
108. A(n) object-oriented DBMS is an approach to data management that stores both data and
procedures acting on the data as objects that can be automatically retrieved and shared.
Difficulty: Easy
Reference:
p. 240
109. Normalization is the process of creating small stable data structures from complex groups of
data when designing a relational database.
Difficulty: Medium
Reference:
p. 241
7-16
Managing Data Resources
Chapter 7
110. A(n) entity-relationship diagram is a method for documenting databases illustrating the
associations between the various persons, places, or things in the database.
Difficulty: Medium
Reference:
p. 242
111. A(n) distributed database is one that is stored in more than one physical location.
Difficulty: Medium
Reference:
p. 242
112. Online analytical processing (OLAP) is the capability for manipulating and analyzing large
volumes of data from multiple perspectives.
Difficulty: Hard
Reference:
p. 244
113. A(n) data warehouse is a database, with reporting and query tools that stores current and
historical data extracted from various operational systems and consolidated for management
reporting and analysis.
Difficulty: Hard
Reference:
p. 245
114. Data mining is the analysis of large pools of data to find patterns and rules that can be used
to guide decision making and predict future behavior.
Difficulty: Medium
Reference:
p. 246
115. A(n) hypermedia database is an approach to data management that organizes data as a
network of nodes linked in any pattern the user specifies; the nodes can contain text,
graphics, sound, full-motion video, or executable programs.
Difficulty: Medium
Reference:
p. 248
116. A(n) application server is software that handles all application operations between browserbased computers and a company’s back-end business applications or databases.
Difficulty: Easy
Reference:
p. 249
117. A(n) database server is a computer in a client/server environment that is responsible for
running a DBMS to process SQL statements and performs database management tasks.
Difficulty: Easy
Reference:
p. 249
118. Data administration is a special organizational function concerned with information policy,
data planning, maintenance of data dictionaries, and data quality standards.
Difficulty: Medium
Reference:
p. 251
119. Information policies are the formal rules governing the maintenance, distribution, and use of
information in an organization.
Difficulty: Medium
Reference:
p. 251
Chapter 7
Managing Data Resources
7-17
120. Database administration refers to the more technical and operational aspects of managing
data, including physical database design and maintenance.
Difficulty: Medium
Reference:
p. 252
Essay Questions
121.
List at least three organizational obstacles to a database environment. Which of the three do
you think is most difficult for the mid-level manager to deal with? As always, support your
opinion.
Implementing a database requires widespread organizational change in the role of
information (and information managers), the allocation of power at senior levels, the
ownership and sharing of information, and patterns of organizational agreement.
122.
What are some of the reasons that moving to a database environment is such a costly, longterm process? List at least four, and describe their impact on the organization.
In addition to the cost of DBMS software, related hardware, and data modeling, the
organizations should anticipate heavy expenditures for integrating, merging, and
standardizing their data so that they can reside in a database that conserves the entire
company. Firms often must spend considerable time merging, cleansing, and standardizing
the data that will populate their database to eliminate inconsistencies, redundancies, and
errors that typically arise when overlapping data are stored and maintained by different
systems and different functional areas.
123.
Describe
.
the typical data hierarchy of the DBMS.
At the lowest level, the bit is the smallest unit of data a computer can handle. A group of this
is a byte, and represents a single character. A named group of characters forming a word, a
group of words, or a number is called a field. A group of related fields comprises a record.
A group of records of the same type is called a file. Related groups of files form a database.
A DBMS provides the software to work with the database and pull information from the data
therein.
124.
List at least three conditions that contribute to data redundancy and inconsistency.
Data redundancy occurs when different divisions, functional areas, and groups in an
organization independently collect the same piece of information. Because it is collected and
maintained in so many different places, the same data item may have different meanings in
different parts of the organization, different names may be used for the same item, and
different descriptions for the same condition. In addition, the fields into which the data is
gathered may have different field names, different attributes, or different constraints.
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Managing Data Resources
125.
What are at least four problems with the traditional file environment? List and describe
them. Which do you think is most difficult for an organization to control? Support your
answer.
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126.
A data definition language
A data manipulation language
A data dictionary
Describe the differences between a data definition language and a data manipulation
language.
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128.
Data redundancy and the attendant confusion
Program-data dependence
Lack of flexibility
Poor security
Lack of data sharing and availability
List and describe the three components of the DBMS.
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127.
Chapter 7
Data definition language is the formal language programmers use to specify
the structure of the content of the database. The data definition language
defines each data element as it appears in the database before that data
element is translated into the forms required by application programs.
Data manipulation language is used in conjunction with some conventional
third – or fourth-generation programming languages to manipulate the data
in the database. This language contains commands that permit end users and
programming specialists to extract data from the database to satisfy
information requests and develop applications. SQL is the standard data
manipulation language for relational DBMS.
Describe the process used in designing a database.
To create a database, one must go through two design exercises: a conceptual design and a
physical design. The conceptual, or logical, design of the database is an abstract model of the
database from a business perspective. The physical design shows how the database is
actually arranged on direct access storage devices. Logical design requires a detailed
description of the business information needs of the actual end users of the database. The
logical database design describes how the data elements in the database are to be grouped.
The design process identifies relationships among data elements and the most efficient way
of grouping data elements together to meet information requirements. Groups of data are
organized, refined, and streamlined until an overall logical view of the relationships among
all the data elements in the database emerges.
The conceptual data model is documented with an entity-relationship diagram representing
the relationship among entities as either one-to-one, one-to-many, or many-to-many.
To use a relational database model effectively, complex groupings of data must be
streamlined to eliminate redundant data elements and awkward many-to-many relationships.
This process is called normalization.
Chapter 7
129.
Managing Data Resources
Describe the two main ways of distributing a database.
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130.
7-19
The central database can be partitioned so that each remote processor has the
necessary data to serve its local area. Changes in local files can be justified
with the central database or on a batch basis, often at night.
The central database can be replicated at all remote locations. Any change
made to the database at one location is automatically replicated at all the
other locations, again usually on a batch basis during off hours.
Describe the differences between a hierarchical and a network DBMS.
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Hierarchical DBMS is used to model one-to-many relationships, presenting data to
users in a treelike structure. Within each record, data elements are organized into
pieces of records called segments. To the user, each record looks like an
organizational chart with one top-level segment called the root. An upper segment is
connected logically to a lower segment in a parent-child relationship. A parent
segment can have more than one child, but a child can have only one parent.
Network DBMS depict data logically as many-to-many relationships. In other
words, parents can have multiple children, and a child can have more than one
parent.