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Database Management SystemsDatabase Management Systems

MIS 421

Dr. Steven C. Ross2001

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Part I: The Context ofPart I: The Context of

Database ManagementDatabase Management The Database Environment

role of databases in organizations

classifications of databases

database vs. file management

Database Development Process

part of the SDLC user/analyst interaction

information engineering and enterprise datamodel

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Chapter 1: The DatabaseChapter 1: The Database

EnvironmentEnvironment

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EvolutionEvolution Data keyed in at run time

INPUT statements

Data stored in the program

DATA and READ statements

Data stored in program-specific files

FORMAT and READ#n statements Data stored in program-independent files

DBMS software

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Data AccessData Access Delimited

97071,Smith,Joe,Woodburn,OR,35.95

97754,Kleindienst,Arthur,Prineville,OR,2998.47

Fixed97071Smith Joe Woodburn OR 35.95

97754Kleindienst Arthur Prineville OR2998.47

Sequential Random

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Disadvantages ofDisadvantages of

Traditional File SystemsTraditional File Systems Program-data dependence

Data redundancy [duplication]

Limited data sharing

Excessive programming and maintenance

effort

Poor data control: homonyms, synonyms

Inadequate data manipulation capabilities

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The Database ApproachThe Database Approach Enterprise data model

high-level entities and associations among them

model of organization

integration of data and processes

Relational databases

data should be related through natural, logical

relationships inherent in the data

tables [relations] made up of rows and columns

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Data, Metadata,Data, Metadata,

Programs, and ObjectsPrograms, and Objects Data Information

Metadata

Programs

Objects

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Advantages of theAdvantages of the

Database ApproachDatabase Approach Program-data independence

Minimal data redundancy

Improved data consistency Improved data sharing

Increased productivity of development staff

Enforcement of standards Improved data quality

Improved data accessibility

Reduced program maintenance

but ...

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Cautions, Costs, and RisksCautions, Costs, and Risks 6Ps: Prior planning prevents p[retty] poor

performance

New, specialized personnel needed

Costly and complex to install and manage

Costly to convert

Backup and recovery more important

Organizational/social issues

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The Range of DatabaseThe Range of Database

ApplicationsApplications Personal [computer] databases

one user, standalone PC

Workgroup databases

1}25 users, LAN

Department databases

25}100 users, linked LANs

Enterprise databases

>100 users, WAN, intranet, VPN

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Chapter 2: DatabaseChapter 2: Database

Development ProcessDevelopment Process

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The Information SystemsThe Information Systems

ArchitectureArchitecture Data: enterprise data model (E-R diagram)

Processes: data flow diagrams

Network: location connectivity diagram

People: context diagram, other DFDs

Events: state transition diagrams

Reasons: decision tables, repository entries

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Information EngineeringInformation Engineering Planning

Analysis

Design Implementation

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Information SystemsP

lanningInformation SystemsP

lanning Step 1: Identify strategic planning factors

goals: what we want to achieve

critical success factors: things we must

accomplish if we are to succeed

problem areas: known weaknesses

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Information SystemsP

lanningInformation SystemsP

lanning Step 2: Identify corporate planning objects

organizational units: how the people (and

resources) are organized

organizational locations: where they work

business functions: what they do

entity types: what they keep track of information systems: existing or proposed

systems

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Information SystemsP

lanningInformation SystemsP

lanning Step 3: Develop an enterprise model

functional decomposition diagram(s)

enterprise data model

matrices [matrixes]

location by function

unit by function information system by data entity

function by data entity

information system by objective

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Strategic Database PlanningStrategic Database Planning[another way of looking at the issues][another way of looking at the issues]

Five year plan

information needs of the functional areas

information needs of the levels of management

information needs of geographical locations

model of the information needs

anticipated data volumes by location

preliminary estimate of costs

recommendations for detailed development

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A Different Version of theA Different Version of the SDLCSDLC Project identification and selection

Project initiation and planning

Analysis

Logical design

Physical design

Implementation

Maintenance

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Database DevelopmentDatabase Development

during theduring the SDLCSDLC Project identification and selection

enterprise modeling

Project initiation and planning & Analysis conceptual data modeling

Logical design logical database design

Physical design physical database designandcreation

Implementation database implementation

Maintenance database maintenance

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Rapid Application DevelopmentRapid Application Development Prototyping

identify problem

develop initial prototype

implement and use prototype

revise and enhance prototype

convert to operational system

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CASE and RepositoryCASE and Repository Drawing

Code generation

Repository

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ThreeThree--Level DatabaseLevel Database

ArchitectureArchitecture External level

users

Conceptual level

systems analysts

Internal level

database programmers/specialists

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ThreeThree--Tiered DatabaseTiered Database

Location ArchitectureLocation Architecture Client tier

Department tier

Enterprise tier

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