© Virtual University of Pakistan Database Management Systems Lecture - 5
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© Virtual University of Pakistan
DatabaseManagement
Systems
Lecture - 5
© Virtual University of Pakistan
Lecture’s Overview
Database Application Development Process
Preliminary Study of System
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Database Application Development Process
Involves
Database Design
Application Programs
Implementation
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Database DesignA DB Design is a model of a
particular real-world system
It provides a picture of reality
Should be simple and self- explanatory
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Database Development
Process
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Database Development Process
Similar to software development process
Preliminary Study
Requirement Analysis
DB Design
Physical Design
Implementation
Maintenance
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Design StagesAnalyze User Environment
Develop Conceptual Model
Map Conceptual Model to Logical
Choose DBMS
Develop Physical Design
Implement System
Test System
Operational Maintenance
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Analyze Existing System
Objective: To understand the working of existing system
Analyze users’ requirements
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Tool Used
Why to use at all?
Data Flow Diagrams
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Data Flow Diagrams
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Data Flow Diagrams (DFDs)
Represent the flow of data flow of data
between different processes between different processes
within a systemwithin a system
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Data Flow DiagramsSimple & intuitive, not focusing on
detailsTo describe, what users dowhat users do,
rather than what computers do
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Data Flow Diagrams Limitations
Focus only on flows of information Decision points/basis not included
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DFD-Symbols Dataflows: pipelines through
which packets of information flow. Arrows are labeled with name of the data that moves through
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DFD-SymbolsData Store
Repositories of data in systemStatic dataData held for processingName is a noun phrase
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DFD-Symbols Process
transforms incoming data flow into outgoing data flow
OR
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DFD-Process
NumberedName is verb/object phrase; Noun for high-level systems
OR1.0
Process1.0
Process
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DFD-SymbolsExternal EntitiesSources/destinations for dataOutside the systemName is Noun Phrase
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DFD-SymbolsCollector
Several data flows combine here
No processing occurs here
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DFD-SymbolsSeparator
Several data flows split from here
No processing
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DFD-SymbolsRing-sum operator
Shows two possible data flows
Only one is followed
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DFD-SymbolsAND operator
Shows two data flows
Both are followed
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Types of DFD
Context diagram
Level 0 diagram
Detailed diagram
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Context DiagramConsists of single
Process/System
Represents the system/process being analyzed
Name: Usually a Noun phrase
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Context DiagramShow Context Only
Inputs/outputs
External Entities
No Data Stores
No flows between external entities
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Context Diagram
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Context Diagram
Registrar
DeanStudent
Faculty Member
Class RequestsSchedule
Student DataCourse Offerings
Class Counts
Faculty Load Sheets
Class Lists
AdmissionSystem
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Diagram 01.0
ProcessRequests
3.0CreateStudent
File
4.0CreateClassFile
7.0ProduceFacultyLoad
Sheets
Registrar
Student
Faculty member Dean
ClassRegistration
C
2.0ProduceStudent
Schedule
ClassRequests
RequestStatus
Old Class Data
UpdatedClass Data
UpdatedStudentData
StudentRegistration
S6.0
ProduceClass
Counts
5.0Produce
ClassLists
StudentData
CourseOffering
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That is all for lecture 5, however, Due to time available discussedLevel 0 diagram in air, to be includedLater inshAllah
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Registrar
DeanStudent
Faculty Member
Class RequestsSchedule
Student DataCourse Offerings
Class Counts
Faculty Load Sheets
Class Lists
AdmissionSystem
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© Virtual University of Pakistan
Diagram 01.1
ProcessRequests
3.0CreateStudent
File
4.0CreateClassFile
7.0ProduceFacultyLoad
Sheets
Registrar
Student
Faculty member Dean
ClassRegistration
C
2.0ProduceStudent
Schedule
ClassRequests
InvalidRequest
Old Class Data
UpdatedClass Data
UpdatedStudentData
StudentRegistration
S6.0
ProduceClass
Counts
5.0Produce
ClassLists
StudentData
CourseOffering
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Detailed Diagram
Student
ClassRequests
InvalidRequest
1.1Edit
Requests
1.2CheckClass
CountsValid
Requests
ClassRegistrationC
1.4UpdateClassData
Upd
ated
Cla
ss D
ata
Old Class
DataAccepted
Request
1.3UpdateStudent
Data
StudentRegistration
S
Accepted
Request
Rejected Request
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© Virtual University of Pakistan
Overview
Continue discussion on DFD
Discussion on Design Phase
Database Design and Data Models
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DatabaseManagement
Systems
Lecture - 5
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