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Using Management Information Systems
David Kroenke
Database Processing
Chapter 4
© 2007 Prentice Hall, Inc.
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Learning Objectives
Know the purpose of database processing.
List the components of a database system.
Understand important database terms.
Know the elements of the entity-relationship
model.
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Learning Objectives (Continued)
Understand the general nature of database
design.
Recognize the need for and know the basic
tasks of database administration .
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Purpose of a Database
The purpose of a database is to keep track of
things that involve more than one theme.
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Figure 4-1 A List of Student Grades
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Figure 4-2 Student Data Shown in Form from
Database
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What Is a Database?
A database is a self-describing collection of
integrated records.
A byte is a character of data.
Bytes are grouped into columns, such as Student
Number and Student Name.
Columns are also called fields.
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What Is a Database? (Continued)
Columns or fields, in turn, are grouped into rows,
which are also called records.
There is a hierarchy of data elements.
A database is a collection of tables plus
relationships among the rows in those tables, plus
special data, called metadata.
Metadata describes the structure of the database.
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Figure 4-3 Student Table (also called File)
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Figure 4-4 Hierarchy of Data Elements
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Relationships Among Records
A key is a column or group of columns that
identifies a unique row in a table.

Student Number is the key of the Student table.
A foreign key is a non-key column or field in one
table that links to a primary key in another table.

Student Number in the Email and Office_Visit tables
Relational databases store their data in the form of
tables that represent relationships using foreign
keys.
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Figure 4-5 Components of a Database
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Figure 4-6 Examples of Relationships Among Rows
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Metadata
Databases are self-describing because they
contain not only data, but also data about the data
in the database
.
Metadata are data that describe data.
The format of metadata depends on the software
product that is processing the database.
Field properties describe formats, a default value
for Microsoft Access to supply when a new row is
created, and the constraint that a value is required
for the column.
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Metadata (Continued)
The presence of metadata makes databases much
more useful.
Because of metadata, no one needs to guess,
remember, or even record what is in the database.
Metadata make databases easy to use for both
authorized and unauthorized purposes.
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Figure 4-7 Example Metadata (in Access)
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Components of a Database Application System
By itself database, is not very useful.
Pure database data are correct, but in raw form
they are not pertinent or useful.
Database applications make database data more
accessible and useful.
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Components of a Database Application System
(Continued)
Users employ a database application that consists
of forms, formatted reports, queries, and application
programs.
Each of these, in turn, calls on the database
management system (DBMS) to process the
database tables.
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Figure 4-8 Components of a Database Application
System
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Database Management System
A database management system (DBMS) is a
program used to create, process, and administer a
database.
Almost no organization develops its own DBMS.
Companies license DBMS products from vendors
like IBM, Microsoft, Oracle, and others.
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Database Management System (Continued)
Popular DBMS products are:



DB2 from IBM
Access and SQL Server from Microsoft
MySQL, an open-source DBMS product that is free for
most applications
The DBMS and the database are two different
things:


A DBMS is a software program.
A database is a collection of tables, relationships, and
metadata.
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Creating the Database and Its Structures
Database developers use the DBMS to create
tables, relationships, and other structures in the
database.
A form can be used to define a new table or to
modify an existing one.
To create a new table, the developer just fills out a
new form.
To modify an existing table say, to add a new
column, the developer opens the metadata form for
that table and adds a new row of metadata.
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Figure 4-9 Adding a New Column to a Table
(in Access)
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Processing the Database
The second function of the DBMS is to process the
database.
Applications use the DBMS for four operations:
read, insert, modify, or delete data.
The applications call upon the DBMS in different
ways:



Via a form, when the user enters new or changed data
Via a computer program behind the form calls the DBMS
to make the necessary database changes
Via an application program, the program calls the DBMS
directly to make the change
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Processing the Database (Continued)
Structured Query Language (SQL) is an
international standard language for processing a
database.
All five of the DBMS products mentioned earlier
accept and process SQL statements.
SQL can be used to create databases and
database structures.
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Administering the Databases
A third DBMS function is to provide tools in the
administration of the database.
Database administration involves a wide variety of
activities.

For example, the DBMS can be used to set up a security
system involving user accounts, passwords, permissions,
and limits for processing the database

DBMS administrative functions also include:
 Backing up database data
 Adding structures to improve the performance of
database applications
 Removing data that are no longer wanted or needed,
and similar tasks
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Database Applications
A database application is a collection of forms,
reports, queries, and application programs that
process a database.
A database may have one or more applications,
and each application may have one or more
users.
Applications have different purposes, features,
and functions, but they all process the same
inventory data stored in a common database.
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Figure 4-10 Use of Multiple Database Applications
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Forms, Reports, and Queries
Data entry forms are used to read, insert, modify,
and delete data.
Reports show data in a structured content.

Some reports also compute values as they present the
data.
DBMS programs provide comprehensive and
robust features for querying database data.
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Figure 4-11 Example Student Report
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Figure 4-12 Example Query
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Database Application Programs
Application programs process logic that is specific
to a given business need.
Application programs enable database processing
over the Internet.


For this use, the application program serves as an
intermediary between the Web server and the
database.
The application program responds to events, such as
when a user presses a submit button; it also reads;
inserts; modifies; and deletes database data.
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Figure 4-13 Four Application Programs on Web
Server Computer
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Multi-User Processing
Multi-user processing is common, but it does pose
unique problems that you, as a future manager,
should know about .
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Multi-User Processing (Continued)
When more that one user is trying to access a
particular database table at same time, the first
user to gain assess to the database table has the
the correct content value, the other users may not
have the correct content value because the first
user may modify the value without the other users
knowing.


This problem is known as the lost-update problem,
exemplifies one of the special characteristics of multiuser database processing.
To prevent this problem, some type of locking must be
used to coordinate the activities of users who know
nothing about one another.
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Multi-User Processing (Continued)
Converting to a single-user database to a multiuser database requires more than simply
connecting another computer.
The logic of the underlying application processing
needs to be adjusted as well.
Be aware of possible data conflicts when you
manage business activities that involve multi-user
processing.
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Enterprise DBMS Versus Personal DBMS
DBMS products fall into two broad categories:
Enterprise DBMS and Personal DBMS.
Enterprise DBMS


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
These products process large organizational and
workgroup databases.
These products support many users, perhaps thousands,
of users and many different database applications.
Such DBMS products support 24/7 operations and can
manage dozens of different magnetic disks with hundreds
of gigabytes or more data.
IBM’s DB2, Microsoft’s SQL Server, and Oracle are
examples of enterprise DBMS products.
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Enterprise DBMS Versus Personal DBMS
(Continued)
Personal DBMS




These products are designed for smaller, simpler
database applications.
Such products are used for personal or small workgroup
applications that involve fewer than 100 users, and
normally fewer than 15.
The great bulk of databases in this category have only a
single user.
Microsoft Access is the only available personal DBMS.
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Figure 4-14 Personal Database System
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Developing a Database Application
The reason that user involvement is so important
for database development is that the database
design depends entirely on how users view their
business environment.
Database structures can be complex, in some
cases, very complex.
Before building, the database, the developers
construct a logical representation of database
data called a data model.
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Developing a Database Application (Continued)
The data model describes the data and
relationships that will be stored in the database.
The data model is referred to as a blueprint.
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Figure 4-15 Database Development Process
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Entities
An entity is something that the users want to track.

Examples of entities are Order, Customer, Salesperson,
and Item
Some entities represent a physical object, such as
an Item or Salesperson; others represent a logical
construct of transaction, such as Order or Contact.
Entities have attributes that describe characteristics
of the entity.

Example attributes of Salesperson are
SalespersonName, Email, Phone, and so forth
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Entities (Continued)
Entities have an identifier, which is an attribute (or
group of attributes) whose value is associated with
one and only one entity instance.



For example, OrderNumber is an identifier of Order,
because only one Order instance has a given value of
OrderNumber.
CustomerNumber is an identifier of Customer.
If each member of the sales staff has a unique name,
then SalespersonName is an identifier of Salesperson.
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Figure 4-16 Student Data Model Entities
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Relationships
Entities have relationships to each other.

An Order, for example, has an relationship to Customer
entity and also to a Salesperson entity
Database designers use diagrams called entityrelationship (E-R) diagrams.
All of the entities of one type are represented by a
single rectangle.
A line is used to represent a relationship between
two entities.
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Relationships (Continued)
If two entities have a plain straight line between
them, then this type of relationship is called one-toone.
If two entities have a line between them, but at the
end of one line in one of the two directions (left or
right) exists an arrow (crow’s foot), then this type
of relationship is called one-to-many.
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Relationships (Continued)
If two entities have a line between them, but at the
end of the line in both directions (left and right)
exists an arrow (crow’s foot), then this type of
relationship is called many-to-many.
The crow’s-foot notation shows the maximum
number of entities that can be involved in a
relationship.



This is called the relationship’s maximum cardinality.
Common examples of maximum cardinality are 1:N, N:M,
and 1:1.
Constraints on minimum requirements are called
minimum cardinalities.
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Figure 4-17 Example of Department, Adviser, and
Student Entities and Relationships
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Figure 4-18 Example of Relationships-Version 1
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Figure 4-19 Example Relationships-Version 2
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Figure 4-20 Example Relationships Showing
Minimum Cardinalities
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Database Design
Database design is the process of converting a data
model into tables, relationships, and data
constraints.
The database design team transforms entities into
tables and expresses relationships by defining
foreign keys.
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Normalization
Normalization is the process of converting poorly
structured tables into two or more well-structured
tables.
Data Integrity Problems
For example, suppose for a given table, the value for a
defined attribute is changed correctly in two rows, but not in
the third
 The table has what is called a data integrity problem:
 Some rows indicate that the name of the attribute is
one value and another row indicates that the name of
the value of the attribute is another. This is called multivalue.
 Data integrity problems are serious.
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Normalization (Continued)
Data Integrity Problems (Continued)
 A table that has data integrity problems will produce
incorrect and inconsistent information.
 Users will lose confidence in the information, and the
system will develop a poor reputation.
 Information systems with poor reputations become
serious burdens to the organizations that use them.
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Figure 4-21 A Poorly Designed Employee Table
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Figure 4-21 A Poorly Designed Employee Table
(Continued)
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Normalization (Continued)
Normalizing for Data Integrity
 The data integrity problem can occur only if data are
duplicated.
 Because of this, one easy way to eliminate the problem is
to eliminate the duplicated data.
 This can be done by transforming the table into two
tables.
 Because such joining of tables is common, DBMS
products have been programmed to perform it efficiently,
but it still requires work.
 Dealing with such trade-offs is an important consideration
in database design.
 The general goal of normalization is to construct tables
such that every table has a single topic or theme.
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Normalization (Continued)
Normalizing for Data Integrity (continued)
 Database practitioners classify tables into various normal
forms according to the kinds of problems they have.
 Transforming a table into a normal form to remove
duplicated data and other problems is called normalizing
the table.
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Figure 4-22 Two Normalized Tables
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Figure 4-23 Transforming a Data Model into a
Database Design
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Figure 4-24 Representing a 1:N Relationship
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Figure 4-24 Representing a 1:N Relationship
(Continued)
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Figure 4-25 Representing a N:M Relationship
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Importance of User’s Review
Users are the final judges as to what data the
database should contain and how records in the
database should be related to one another.
The easiest time to change the database structure is
during the data modeling stage.
However, once the database has been constructed,
loaded with data, and application forms, reports,
queries, and application programs created, changing a
relationship means weeks of work.
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Importance of User’s Review (Continued)
When a database is developed for your use, you must
carefully review the data model.
If you do not understand any aspect of it, you should
ask for clarification until you do.
The data model must accurately reflect your view of
the business.
Do not proceed unless the data model is correct.
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Database Administration
In light of both the importance and the management
challenges of databases, most organizations have
created a staff function called database
administration.
In smaller organizations, this function is usually served
by a single person, sometimes even on a part-time
basis.
Larger organizations assign several people to an
office of database administration.
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Database Administration (Continued)
Depending on the context, the letters DBA either
stand for the database administrator or for the office of
database administration.
The purpose of database administration is to manage
the development, operation, and maintenance of a
database so as to achieve the organization’s
objectives.
This function requires balancing conflicting goals:
protecting the database while maximizing its
availability for authorized use.
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Figure 4-26 Summary of Database Administrative
Tasks
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DBA Development Responsibilities
The DBA is not a user of the database or any of its
applications.
The DBA is an auditor, a consultant, sometimes a
policeman, and a diplomat who works as a liaison
between the users and professional developers.
One of the first tasks for the DBA is to create a
steering committee that consists of key users.
The DBA uses the committee as a forum for
community-wide decisions regarding the development,
use, and maintenance of the database.
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DBA Operations Responsibilities
An important DBA function is to establish communitywide policies for the processing of the database.
The DBA uses the steering committee to determine
processing rights for each column of each table.


These rights include what data users are authorized to read,
create, modify, and delete.
The DBA also works with development personnel to ensure
that a security system is in place to enforce these
processing rights.
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DBA Backup and Recovery Responsibilities
As a protector of the database, the DBA has the
responsibility to ensure that appropriate procedures
and policies exist for backing up the database and that
those procedures are followed.
The DBA needs to ensure that users and operations
personnel are appropriately trained with regard to
backup and recovery procedures.
Finally when failures occur, in many organizations the
DBA is responsible for managing the recovery
process.
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DBA Responsibilities for Adaptation
Over time, requirements for the database will change.
Changes that benefit one group in the organization
may not benefit other groups.
The DBA needs to set up a system for recording and
tracking requests for changes.
The responsibility of the DBA is to provide the forum
and to ensure that requests are considered and acted
upon in a responsible manner.
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Is the DBA a Technical Person?
The DBA function has broad managerial
responsibilities for the database.
Part of the DBA function is technical:



Monitoring performance
Managing the DBMS
Developing backup and recovery procedures
For larger organizations, and for databases that touch
many different departments and business functions,
the DBA’s job is more diplomatic than technical.
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Summary
The purpose of a database is to keep track of
things.
A database is a self-describing collection of
integrated records.
With the relational model, data are stored in
tables and relationships are represented by
column values.
A key, or table key, is a column or group of
columns that uniquely identifies a row.
A foreign key is a column or group of columns in
one table that identifies a row in a second table.
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Summary (Continued)
Metadata are data that describe data.
A database application system includes the
database, the database management system
(DBMS), and database applications.
The DBMS is a program used to create, process,
and administer a database.
Structured Query Language (SQL) is an
international standard for defining and processing
database data.
A database application consists of forms, reports,
queries, and application programs.
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Summary (Continued)
A data model is a logical representation of a
database that describes data and relationships.
An entity is something that users want to track.
Entities have relationships to one another.
Database design is the process of converting a
data model into tables, relationships, and data
construction.
Normalization is the process of converting poorly
structured tables into tables that are well
structured.
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Key Terms and Concepts
Access
Attribute
Byte
Column
Crow’s foot
Crow’s-foot diagram version
Data integrity problem
Data model
Database
Database administration
Database application
system
Database management system
(DBMS)
DBA
DB2
Enterprise DBMS
Entity
Entity-relationship (E-R) data
model
Entity-relationship (E-R)
diagram
Field
File
Firewall
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Key Terms and Concepts (Continued)
Foreign key
Form
Identifier
Key
Lost-update problem
Maximum cardinality
Metadata
Minimum cardinality
Multi-user processing
MySQL
Object-relational database
1:N(one-to-many)
relationship
N:M (many-to-many)
relationship
Normal forms
Normalization
Oracle
Query
Personal DBMS
Record
Relation
Relational database
Relationship
Report
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Key Terms and Concepts (Continued)
Row
SQL Server
Structured Query Language
(SQL)
Table
Unified Modeling Language
(UML)
User account
User role
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Ethics Guide–Nobody Said I Shouldn’t
Kelly make a backup copy of his company’s
database on CD and took it home and installed it
on his home computer.
While performing queries on the database, he
found customer order information and focused in
on his friend Jason’s customer order entries.
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Ethics Guide–Nobody Said I Shouldn’t (Continued)
Kelly noticed that Jason gave huge discounts to
Valley Appliances but not to his other customers.
At an after work gathering, Kelly asked Jason
about the Valley Appliances discount telling him
what he had been doing.
When Kelly returned to work, he was fired.
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Security Guide–Database Security
The firewall, a computing device located between a
firm’s internal network and external networks,
prevents unauthorized access to the internal
network.
For the best security, the DBMS computer should
be protected by a firewall, and then all other
security measures should be designed as if the
firewall has been breached.
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Security Guide–Database Security (Continued)
All operating systems and DBMS patches should
be installed as soon as they become available.
To prevent unauthorized access, no one other than
authorized operations personnel should be able to
directly access the computer that runs the DBMS.

Instead, all access should be via authorized applications
programs
The computer running the DBMS should be
secured behind locked doors, and visits to that
room should be recorded in a log.
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Security Guide–Database Security (Continued)
All major DBMS products have extensive, built-in
security features.




These features allow for the definition of user accounts
and user roles.
Each user account belongs to a specific person.
A role is a generic employee function, such as payroll
clerk or field salesperson.
Once an account is defined, it can be assigned specific
permissions, and it can also be assigned particular roles.
Most DBMS products log failed attempts to sign on
and produce other usage reports as well.
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Security Guide–Database Security (Continued)
The database administrator (DBA) should
periodically monitor such logs and reports for
suspicious activity.
It is important to have a plan of action for security
emergencies.
The steps to be taken vary from database to
database.
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Problem Solving Guide–Immanuel Kant, Data
Modeler
Only the users can say whether a data model
accurately reflects their business environment.
What happens when the user’s disagree among
themselves?


It’s tempting to say, “The correct model is the one that
better represents the real world.” The problem with this
statement is that data models do not model “the real
world.”
A data model is simply a model of what the data
modeler perceives.
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Problem Solving Guide–Immanuel Kant, Data
Modeler (Continued)
What happens when the user’s disagree among
themselves? (continued)

This very important point can be difficult to understand;
but if you understand it, you will save many hours in
data modeling validation meetings and be a much better
data modeling member.
Nothing that humans can do represent the real
world.


A data model, therefore, is a model of a human’s model
of what appears to be “out there.”
For example, a model of a salesperson is a model of the
model that humans make of salespeople.
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Problem Solving Guide–Immanuel Kant, Data
Modeler (Continued)
What do we do when people disagree about what
should be in a data model?



First, we realize that anyone attempting to justify her
data model as a better representation of the real world
is saying, quite arrogantly, “The way I think of the world
is the way that counts.”
Second, in times of disagreement we must ask the
question, “How well does the data model fit the mental
models of the people who are going to use the system?”
The only valid point is whether it reflects how the users
view their world.
 Will it enable the users to do their jobs?
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Opposing Forces Guide–No, Thanks, I’ll Use a
Spreadsheet
I’m not buying all this stuff about databases.






“I’ve tried them and they’re a pain-way too complicated to
set up, and most of the time, a spreadsheet works just as
well.”
“No, unless you are a General Motors or Toyota, I
wouldn’t mess with a database.”
“You have to have professional IS people to create it and
keep it running.”
“Besides, I don’t really want to share my data with
anyone.”
“I work pretty hard to develop my client list.”
“Why would I want to give it away?”
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Opposing Forces Guide–No, Thanks, I’ll Use a
Spreadsheet (Continued)
I’m not buying all this stuff about databases
(continued)




“When I want something, I use Excel’s Data Filter.”
“I can usually get what I need.”
“Of course, I can’t still send form letters, but it really
doesn’t matter.”
“I get most of my sales using the phone, anyway.”
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Reflection Guide–Requirements Creep
Changing requirements is the biggest challenge for
creating and managing databases and database
applications.



The development team just finishes the order entry
database and applications when a user asks, innocently
enough, “Where do I enter the second salesperson?”
The development team responds “This is the first time
I’ve heard of it. Why didn’t someone tell me this before?”
Of course, the best way to solve this problem is not to
have it in the first place; it would be better to learn of the
need for multiple salesperson’s names long before the
system is created.
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Reflection Guide–Requirements Creep
(Continued)
It is very important for user involvement in both
requirements specification and data model
validation.
Unfortunately, however, not all change requests are
preventable.

Some occur only after a period of system use.
An information system enables its users to behave
in new ways, and as they behave in new ways, they
think of new requirements for the system.
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Reflection Guide–Requirements Creep
(Continued)
As the system is adapted to add new features, the
users again will be able to behave in new ways,
and they will then think of yet additional features
and functions.
The bottom line is there will always be new
requirements for an information system.
The users and the development team must specify
all the requirements that they know about and
validate the data model as best they can.
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