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8/8/2019 421 Chap 0102
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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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