SOLUTION AND ANSWER GUIDE
DATABASE SYSTEMS: DESIGN, IMPLEMENTATION AND
MANAGEMENT
14TH EDITION
CHAPTER NO. 01: DATABASE SYSTEMS
TABLE OF CONTENTS
• Answers to review questions
• Answers to problems
ANSWERS TO REVIEW QUESTIONS
1. Define each of the following terms:
Answer:
a. data
Raw facts from which the required information is derived. Data have little meaning unless they are
grouped in a logical manner.
b. field
A character or a group of characters (numeric or alphanumeric) that describes a specific characteristic.
A field may define a telephone number, a date, or other specific characteristics that the end user wants
to keep track of.
c. record
A logically connected set of one or more fields that describes a person, place, event, or thing. For
example, a CUSTOMER record may be composed of the fields CUST_NUMBER, CUST_LNAME,
CUST_FNAME, CUST_INITIAL, CUST_ADDRESS, CUST_CITY, CUST_STATE,
CUST_ZIPCODE, CUST_AREACODE, and CUST_PHONE.
d. file
Historically, a collection of file folders, properly tagged and kept in a filing cabinet. Although such
manual files still exist, we more commonly think of a (computer) file as a collection of related records
that contain information of interest to the end user. For example, a sales organization is likely to keep a
file containing customer data. Keep in mind that the phrase related records reflects a relationship
based on function. For example, customer data are kept in a file named CUSTOMER. The records in
this customer file are related by the fact that they all pertain to customers. Similarly, a file named
PRODUCT would contain records that describe products—the records in this file are all related by the
fact that they all pertain to products. You would not expect to find customer data in a product file, or
vice versa.
, NOTE
Field, record, and file are computer terms, created to help describe how data are
stored in secondary memory. Emphasize that computer file data storage does not
match the human perception of such data storage.
2. What is data redundancy, and which characteristics of the file system can lead to it?
Answer: Data redundancy exists when unnecessarily duplicated data are found in the database. For
example, a customer’s telephone number may be found in the customer file, in the sales agent file, and
in the invoice file. Data redundancy is symptomatic of a (computer) file system, given its inability to
represent and manage data relationships. Data redundancy may also be the result of poorly designed
databases that allow the same data to be kept in different locations. (Here's another opportunity to
emphasize the need for good database design!)
3. What is data independence, and why is it lacking in file systems?
Answer: Data independence is a condition in which the programs that access data are not dependent
on the data storage characteristics of the data. Systems that lack data independence are said to exhibit
data dependence. File systems exhibit data dependence because file access is dependent on a file’s data
characteristics. Therefore, any time the file data characteristics are changed, the programs that access
the data within those files must be modified.
Data independence exists when changes in the data characteristics don’t require changes in the
programs that access those data. File systems lack data independence because all data access programs
are subject to change when any of the file system’s data storage characteristics—such as changing a
data type—change.
4. What is a DBMS, and what are its functions?
Answer: A DBMS is best described as a collection of programs that manage the database structure and
that control shared access to the data in the database. Current DBMSs also store the relationships
between the database components; they also take care of defining the required access paths to those
components. The functions of a current-generation DBMS may be summarized as follows:
• The DBMS stores the definitions of data and their relationships (metadata) in a data
dictionary; any changes made are automatically recorded in the data dictionary.
• The DBMS creates the complex structures required for data storage.
• The DBMS transforms entered data to conform to the data structures in the previous item.
• The DBMS creates a security system and enforces security within that system.
• The DBMS creates complex structures that allow multiple-user access to the data.
• The DBMS performs backup and data recovery procedures to ensure data safety.
• The DBMS promotes and enforces integrity rules to minimize data integrity problems.
• The DBMS provides access to the data via utility programs and from programming languages
interfaces.
• The DBMS provides end-user access to data within a computer network environment.
,5. What is structural independence, and why is it important?
Answer: Structural independence exists when data access programs are not subject to change when the
file’s structural characteristics, such as the number or order of the columns in a table, change. Structural
independence is important because it substantially decreases programming effort and program
maintenance costs.
6. Explain the differences among data, information, and a database.
Answer: Data are raw facts. Information is processed data to reveal the meaning behind the facts.
Let’s summarize some key points:
• Data constitute the building blocks of information.
• Information is produced by processing data.
• Information is used to reveal the meaning of data.
• Good, relevant, and timely information is the key to good decision making.
• Good decision making is the key to organizational survival in a global environment.
A database is a computer structure for storing data in a shared, integrated fashion so that the data can
be transformed into information as needed.
7. What is the role of a DBMS, and what are its advantages? What are its disadvantages?
Answer: A database management system (DBMS) is a collection of programs that manages the
database structure and controls access to the data stored in the database. Figure 1.4 (shown in the text)
illustrates that the DBMS serves as the intermediary between the user and the database. The DBMS
receives all application requests and translates them into the complex operations required to fulfill
those requests. The DBMS hides much of the database’s internal complexity from the application
programs and users. The application program might be written by a programmer using a programming
language such as COBOL, Visual Basic, or C++, or it might be created through a DBMS utility
program.
Having a DBMS between the end user’s applications and the database offers some important
advantages. First, the DBMS enables the data in the database to be shared among multiple applications
or users. Second, the DBMS integrates the many different users’ views of the data into a single all-
encompassing data repository.
Because data are the crucial raw material from which information is derived, you must have a good
way of managing such data. As you will discover in this book, the DBMS helps make data
management more efficient and effective. In particular, a DBMS provides advantages such as:
• Improved data sharing. The DBMS helps create an environment in which end users have
better access to more and better-managed data. Such access makes it possible for end users to
respond quickly to changes in their environment.
• Improved data security. A DBMS provides a framework for better enforcement of data
privacy and security policies.
• Better data integration. Wider access to well-managed data promotes an integrated view of
the organization’s operations and a clearer view of the big picture. It becomes much easier to
see how actions in one segment of the company affect other segments.
, • Minimized data inconsistency. Data inconsistency exists when different versions of the same
data appear in different places. For example, data inconsistency exists when a company’s
sales department stores a sales representative’s name as “Bill Brown” and the company’s
personnel department stores that same person’s name as “William G. Brown” or when the
company’s regional sales office shows the price of product “X” as $45.95 and its national
sales office shows the same product’s price as $43.95. The probability of data inconsistency is
greatly reduced in a properly designed database.
• Improved data access. The DBMS makes it possible to produce quick answers to ad hoc
queries. From a database perspective, a query is a specific request for data manipulation (e.g.,
to read or update the data) issued to the DBMS. Simply put, a query is a question and an ad
hoc query is a spur-of-the-moment question. The DBMS sends back an answer (called the
query result set) to the application. For example, end users, when dealing with large amounts
of sales data, might want quick answers to questions (ad hoc queries) such as:
What was the dollar volume of sales by product during the past six months?
What is the sales bonus figure for each of our salespeople during the past three
months?
How many of our customers have credit balances of $3,000 or more?
• Improved decision making. Better-managed data and improved data access make it possible to
generate better-quality information, on which better decisions are based.
• Increased end-user productivity. The availability of data, combined with the tools that
transform data into usable information, empowers end users to make quick, informed
decisions that can make the difference between success and failure in the global economy.
The advantages of using a DBMS are not limited to the few just listed. In fact, you will discover many
more advantages as you learn more about the technical details of databases and their proper design.
Although the database system yields considerable advantages over previous data management
approaches, database systems do carry significant disadvantages. For example:
• Increased costs. Database systems require sophisticated hardware and software and highly
skilled personnel. The cost of maintaining the hardware, software, and personnel required to
operate and manage a database system can be substantial. Training, licensing, and regulation
compliance costs are often overlooked when database systems are implemented.
• Management complexity. Database systems interface with many different technologies and have a
significant impact on a company’s resources and culture. The changes introduced by the adoption of
a database system must be properly managed to ensure that they help advance the company’s
objectives. Given the fact that database systems hold crucial company data that are accessed from
multiple sources, security issues must be assessed constantly.
• Maintaining currency. To maximize the efficiency of the database system, you must
keep your system current. Therefore, you must perform frequent updates and apply
the latest patches and security measures to all components. Because database
technology advances rapidly, personnel training costs tend to be significant.
• Vendor dependence. Given the heavy investment in technology and personnel
training, companies might be reluctant to change database vendors. As a
consequence, vendors are less likely to offer pricing point advantages to existing
customers, and those customers might be limited in their choice of database system
components.
DATABASE SYSTEMS: DESIGN, IMPLEMENTATION AND
MANAGEMENT
14TH EDITION
CHAPTER NO. 01: DATABASE SYSTEMS
TABLE OF CONTENTS
• Answers to review questions
• Answers to problems
ANSWERS TO REVIEW QUESTIONS
1. Define each of the following terms:
Answer:
a. data
Raw facts from which the required information is derived. Data have little meaning unless they are
grouped in a logical manner.
b. field
A character or a group of characters (numeric or alphanumeric) that describes a specific characteristic.
A field may define a telephone number, a date, or other specific characteristics that the end user wants
to keep track of.
c. record
A logically connected set of one or more fields that describes a person, place, event, or thing. For
example, a CUSTOMER record may be composed of the fields CUST_NUMBER, CUST_LNAME,
CUST_FNAME, CUST_INITIAL, CUST_ADDRESS, CUST_CITY, CUST_STATE,
CUST_ZIPCODE, CUST_AREACODE, and CUST_PHONE.
d. file
Historically, a collection of file folders, properly tagged and kept in a filing cabinet. Although such
manual files still exist, we more commonly think of a (computer) file as a collection of related records
that contain information of interest to the end user. For example, a sales organization is likely to keep a
file containing customer data. Keep in mind that the phrase related records reflects a relationship
based on function. For example, customer data are kept in a file named CUSTOMER. The records in
this customer file are related by the fact that they all pertain to customers. Similarly, a file named
PRODUCT would contain records that describe products—the records in this file are all related by the
fact that they all pertain to products. You would not expect to find customer data in a product file, or
vice versa.
, NOTE
Field, record, and file are computer terms, created to help describe how data are
stored in secondary memory. Emphasize that computer file data storage does not
match the human perception of such data storage.
2. What is data redundancy, and which characteristics of the file system can lead to it?
Answer: Data redundancy exists when unnecessarily duplicated data are found in the database. For
example, a customer’s telephone number may be found in the customer file, in the sales agent file, and
in the invoice file. Data redundancy is symptomatic of a (computer) file system, given its inability to
represent and manage data relationships. Data redundancy may also be the result of poorly designed
databases that allow the same data to be kept in different locations. (Here's another opportunity to
emphasize the need for good database design!)
3. What is data independence, and why is it lacking in file systems?
Answer: Data independence is a condition in which the programs that access data are not dependent
on the data storage characteristics of the data. Systems that lack data independence are said to exhibit
data dependence. File systems exhibit data dependence because file access is dependent on a file’s data
characteristics. Therefore, any time the file data characteristics are changed, the programs that access
the data within those files must be modified.
Data independence exists when changes in the data characteristics don’t require changes in the
programs that access those data. File systems lack data independence because all data access programs
are subject to change when any of the file system’s data storage characteristics—such as changing a
data type—change.
4. What is a DBMS, and what are its functions?
Answer: A DBMS is best described as a collection of programs that manage the database structure and
that control shared access to the data in the database. Current DBMSs also store the relationships
between the database components; they also take care of defining the required access paths to those
components. The functions of a current-generation DBMS may be summarized as follows:
• The DBMS stores the definitions of data and their relationships (metadata) in a data
dictionary; any changes made are automatically recorded in the data dictionary.
• The DBMS creates the complex structures required for data storage.
• The DBMS transforms entered data to conform to the data structures in the previous item.
• The DBMS creates a security system and enforces security within that system.
• The DBMS creates complex structures that allow multiple-user access to the data.
• The DBMS performs backup and data recovery procedures to ensure data safety.
• The DBMS promotes and enforces integrity rules to minimize data integrity problems.
• The DBMS provides access to the data via utility programs and from programming languages
interfaces.
• The DBMS provides end-user access to data within a computer network environment.
,5. What is structural independence, and why is it important?
Answer: Structural independence exists when data access programs are not subject to change when the
file’s structural characteristics, such as the number or order of the columns in a table, change. Structural
independence is important because it substantially decreases programming effort and program
maintenance costs.
6. Explain the differences among data, information, and a database.
Answer: Data are raw facts. Information is processed data to reveal the meaning behind the facts.
Let’s summarize some key points:
• Data constitute the building blocks of information.
• Information is produced by processing data.
• Information is used to reveal the meaning of data.
• Good, relevant, and timely information is the key to good decision making.
• Good decision making is the key to organizational survival in a global environment.
A database is a computer structure for storing data in a shared, integrated fashion so that the data can
be transformed into information as needed.
7. What is the role of a DBMS, and what are its advantages? What are its disadvantages?
Answer: A database management system (DBMS) is a collection of programs that manages the
database structure and controls access to the data stored in the database. Figure 1.4 (shown in the text)
illustrates that the DBMS serves as the intermediary between the user and the database. The DBMS
receives all application requests and translates them into the complex operations required to fulfill
those requests. The DBMS hides much of the database’s internal complexity from the application
programs and users. The application program might be written by a programmer using a programming
language such as COBOL, Visual Basic, or C++, or it might be created through a DBMS utility
program.
Having a DBMS between the end user’s applications and the database offers some important
advantages. First, the DBMS enables the data in the database to be shared among multiple applications
or users. Second, the DBMS integrates the many different users’ views of the data into a single all-
encompassing data repository.
Because data are the crucial raw material from which information is derived, you must have a good
way of managing such data. As you will discover in this book, the DBMS helps make data
management more efficient and effective. In particular, a DBMS provides advantages such as:
• Improved data sharing. The DBMS helps create an environment in which end users have
better access to more and better-managed data. Such access makes it possible for end users to
respond quickly to changes in their environment.
• Improved data security. A DBMS provides a framework for better enforcement of data
privacy and security policies.
• Better data integration. Wider access to well-managed data promotes an integrated view of
the organization’s operations and a clearer view of the big picture. It becomes much easier to
see how actions in one segment of the company affect other segments.
, • Minimized data inconsistency. Data inconsistency exists when different versions of the same
data appear in different places. For example, data inconsistency exists when a company’s
sales department stores a sales representative’s name as “Bill Brown” and the company’s
personnel department stores that same person’s name as “William G. Brown” or when the
company’s regional sales office shows the price of product “X” as $45.95 and its national
sales office shows the same product’s price as $43.95. The probability of data inconsistency is
greatly reduced in a properly designed database.
• Improved data access. The DBMS makes it possible to produce quick answers to ad hoc
queries. From a database perspective, a query is a specific request for data manipulation (e.g.,
to read or update the data) issued to the DBMS. Simply put, a query is a question and an ad
hoc query is a spur-of-the-moment question. The DBMS sends back an answer (called the
query result set) to the application. For example, end users, when dealing with large amounts
of sales data, might want quick answers to questions (ad hoc queries) such as:
What was the dollar volume of sales by product during the past six months?
What is the sales bonus figure for each of our salespeople during the past three
months?
How many of our customers have credit balances of $3,000 or more?
• Improved decision making. Better-managed data and improved data access make it possible to
generate better-quality information, on which better decisions are based.
• Increased end-user productivity. The availability of data, combined with the tools that
transform data into usable information, empowers end users to make quick, informed
decisions that can make the difference between success and failure in the global economy.
The advantages of using a DBMS are not limited to the few just listed. In fact, you will discover many
more advantages as you learn more about the technical details of databases and their proper design.
Although the database system yields considerable advantages over previous data management
approaches, database systems do carry significant disadvantages. For example:
• Increased costs. Database systems require sophisticated hardware and software and highly
skilled personnel. The cost of maintaining the hardware, software, and personnel required to
operate and manage a database system can be substantial. Training, licensing, and regulation
compliance costs are often overlooked when database systems are implemented.
• Management complexity. Database systems interface with many different technologies and have a
significant impact on a company’s resources and culture. The changes introduced by the adoption of
a database system must be properly managed to ensure that they help advance the company’s
objectives. Given the fact that database systems hold crucial company data that are accessed from
multiple sources, security issues must be assessed constantly.
• Maintaining currency. To maximize the efficiency of the database system, you must
keep your system current. Therefore, you must perform frequent updates and apply
the latest patches and security measures to all components. Because database
technology advances rapidly, personnel training costs tend to be significant.
• Vendor dependence. Given the heavy investment in technology and personnel
training, companies might be reluctant to change database vendors. As a
consequence, vendors are less likely to offer pricing point advantages to existing
customers, and those customers might be limited in their choice of database system
components.
