Ch 5 Turban IT

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Introduction to Information Technology, 2nd EditionTurban, Rainer & Potter

2003 John Wiley & Sons, Inc.

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Introduction to Information Technology

2nd Edition

Turban, Rainer & Potter


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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Introduction to Information Technology, 2nd

EditionTurban, Rainer & Potter


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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



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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



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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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Introduction to Information Technology, 2

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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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Copyright 2003 John Wiley & Sons, Inc. All rights reserved. Reproductionor translation of this work beyond that permitted in Section 117 of the 1976

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use of the information herein.

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Ch 5 Turban IT