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Introduction to Information Technology
2nd Edition
Turban, Rainer & Potter
2003 John Wiley & Sons, Inc.
Chapter 5:
Managing Organizational Data and
Information
Prepared by:
Roberta M. Roth, Ph.D.
University of Northern Iowa
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Chapter Preview
In this chapter, we will study:
Basic data management terminology
Storing data in traditional files and problemswith this approach
The data base approach to storing data
How data is organized to create a data base
Components of a DBMS
How companies utilize their stored data
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Basics of Data Arrangement
and Access The Data Hierarchy
Recall8 bits => 1 byte => 1 character
Field - a logical grouping of characters into a
word, a small group of words, or a complete
number
Record - a logical grouping of related fields
File -a logical grouping of related records
Database - a logical grouping of related files
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Data Management Terminology
Entity - a person, place, thing, or event about
which information is maintained
Records describe entities
Attribute - each characteristic or quality
describing a particular entity
Fields describe attributes
Primary Key - field that uniquely identifies the
record
Secondary Key - field does not identify the
records uniquely, but can be used to form logical
groups of records
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Storing and Accessing Records
Sequential media (tape) stores records sequentially based
on key values
Direct (or random) media (disks) use other techniques:
Indexed Sequential Access Method (ISAM)
Uses an index to locate individual records
Index - lists the key field of each record and where that record
is physically located
Direct File Access Method
Uses the key field to locate the physical address of a record
Transform algorithm - translates the key field value directly
into the records storage location
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Traditional File Environment
The organization has multiple applications withrelated data files
Each application has a
specific data file related to it,containing all the datarecords needed by the
application
Each application comes withan associated application-
specific data file
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Traditional File Environment (continued)
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Data redundancy same piece of data found inseveral places.
Data inconsistency various copies of data no longeragree.
Data isolation data in several application data files ishard to access and integrate.
Security may be difficult to limit access to various dataitems in applications.
Data integrity data must be accurate and correct.
Application/data dependence applications aredeveloped based on the way data is stored.
Problems: Traditional File Environment
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2003 John Wiley & Sons, Inc.
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Database Management System (DBMS)
Database : The Modern Approach
The database management system provides access tothe data
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Two choices: Centralized or Distributed
Choice will affect user accessibility, query response time,
data entry, security, and cost
Option 1: Centralized databaseAll the related files are in one physical location
Provides database administrators with the ability to work on a
database as a whole at one location
Data consistency is improved and security is easier
Files are only accessible via the centralized host computerRecovery from disasters is easier
Vulnerable to a single point of failure
Speed problem due to transmission delays
Locating Data in Databases
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Option 2: Distributed database
Complete copies of a database, or portions of a
database, are in more than one location, close to the
userType 1: Replicated database
Copies of database in many locations
Reduced single-point-of-failure problems
Increased user access responsiveness
Type 2: Partitioned databases
A portion of the database in each location
Each location responsible for its own data
Locating Data in Databases (continued)
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Locating Data in Databases (continued)
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First, develop a Conceptual design - an abstractmodel of the database from the user or businessperspective
Second, organize with Entity-Relationship (ER)
modelingprocess of planning the database design
Entity classes Instance Identifiers Relationships
Database Development
CourseCourse NumberCourse NameCourse TimeCourse Place
ProfessorID NumberNameDepartment
can have1:M 1:1
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Entity-relationship model
Types of relationships:
One-to-one: a student hasone schedule; a schedule
belongs to one student
One-to-many: a course hasone professor; a professor has
one or more courses
Many-to-many: a studenthas one or more courses; a
course has one or more
students
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Third, analyze the data structure byapplying the Normalization processmethod that reduces a relational database to
its most streamlined formHelps achieve
minimum redundancy
maximum data integrity
best processing performance
Database Development
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Non-normalized table and its problems
* If an order contains many parts, you will have many repeatinggroups of part information. How will you know how much space toset aside for all the groups of part information?
*The customer number, name, address, etc. must be repeated inevery order. If the customer moves, how will you make sure thatall occurrences of the address get updated correctly in all the orderrecords?
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Normalized Relation
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Fourth, physically implement the datastructure in the database managementsystem softwareCreate tables
Define fields and field properties
Establish primary keys
Define table relationships
Add actual data (records) to tables
Database Development
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Database Management Systems
A set of software programs that provide access to
a database
Data is stored in one location, from which it can
be updated and retrieved
Application programs are given access to the
stored data by various mechanisms
Maintaining the integrity of stored information
Managing security and user access
Recovering information when the system fails
Accessing various database functions from within an
application
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Logical view - represents data in a formatthat is meaningful to a user (e.g., tables withfields and records)
Physical view - deals with the actual,physical arrangement and location of data inthe direct access storage devices (DASD)
DBMSs shield the user from having toknow about the physical location of thedata; user only has to know the logicalway its organized
DBMS: Logical versus Physical View
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Data Model
Defines the way data are conceptually structured
Data Definition Language (DDL)
Used to define the content and structure of the database
Users define their logical view (schema) of the databaseusing the DDL
Physical characteristics of records and fields are defined
Relationships, primary keys, and security can beestablished
DBMSComponents
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Data Manipulation Language (DML)
Used to query the contents of the database,
store or update information in the database,
and develop database applicationsStructured query language (SQL) - most
popular relational database language
Data Dictionary
stores definitions of data elements and data
characteristics
More DBMSComponents
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Improved strategic use of corporate data
Reduced complexity of IS environment
Reduced data redundancy and inconsistency
Enhanced data integrity
Application/data independence
Improved security
Reduced development and maintenance costs Improved IS flexibility
Increased data access
DBMSBenefits
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Logical Data Models
A managers ability to use a database depends on how
the database is structured logically and physically.
In a logically structuring database, consider the
characteristics of the data and how the data will be
accessed. Three common data models : hierarchical, network, and
relational
Using these models, database designer can build logical or
conceptual view of data that can then be physicallyimplemented into virtually any database with any DBMS.
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Logical Data Models (continued) Relational model is common in PC environment because it
is simple to understand.
Relational model provides high flexibility and ease of use.
Relational model provides slower search and access times;
a problem in high-volume business settings. Hierarchical data model gives best processing speeds, but
poor query flexibility.
Network data model gives pretty good processing speeds
and pretty good query flexibility, but is very complex.
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Emerging and Specialized Data Models
Multidimensional
Object-oriented data model
Hypermedia
Geographic information system database
Knowledge database
Multimedia database
Small-footprint database
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Using the Stored Data
Access to accurate and timely information is
critical in todays business environment.
Much information is collected by TPS, but access
to and insight from that data may be limited.
Many organizations are working to improve
information access and availability.
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Using the Stored Data (continued)
Data warehouse:a database system designed to support management decision
making.
Emphasis is on organizing data in convenient, meaningful ways so
that users can get their queries answered.
Current and historical, detail and summarized data are included.
Metadata (data about data) is included to help keep track of the
data warehouse content.
Data mart: small scale, simpler data warehouse. Easier
to implement. Targets smaller business segments.
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Using the Stored Data (continued)
Data mining:Extracting new insights from data warehouse
Sophisticated tools employ algorithms to discover
hidden patterns, correlations, and relationships.
Classifying Clustering
Associating
Sequencing
Forecasting
What can we learn (examples)?
Market segments and customer characteristics
Customer buying patterns
Fraudulent behavior
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Chapter Summary
Traditional file structures lead to numerous data
management problems
DBMS help resolve many of those problems
Users are concerned with the logical view of data.
When organizations have created well structured
databases, decision making and insight will
improve through data warehouses and the use of
data mining tools.
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