Database Management Systems Lecture 5 Virtual University of

Database Management Systems Lecture - 5 © Virtual University of Pakistan

Lecture’s Overview ØDatabase Application Development Process ØPreliminary Study of System © Virtual University of Pakistan

Database Application Development Process Involves ØDatabase Design ØApplication Programs ØImplementation © Virtual University of Pakistan

Database Design ØA DB Design is a model of a particular real-world system ØIt provides a picture of reality ØShould be simple and selfexplanatory © Virtual University of Pakistan

Database Development Process © Virtual University of Pakistan

Database Development Process ØSimilar to Preliminary Study software Requirement Analysis development DB Design Physical Design process Implementation Maintenance © Virtual University of Pakistan

Design Stages Analyze User Environment Develop Conceptual Model Map Conceptual Model to Logical Choose DBMS Develop Physical Design Implement System Test System © Virtual University of Pakistan Operational Maintenance

Analyze Existing System ØObjective: To understand the working of existing system ØAnalyze users’ requirements © Virtual University of Pakistan

Tool Used ØWhy to use at all? ØData Flow Diagrams © Virtual University of Pakistan

Data Flow Diagrams © Virtual University of Pakistan

Data Flow Diagrams (DFDs) Ø Represent the flow of data between different processes within a system © Virtual University of Pakistan

Data Flow Diagrams Ø Simple & intuitive, not focusing on details Ø To describe, what users do, do rather than what computers do © Virtual University of Pakistan

Data Flow Diagrams Ø Limitations § Focus only on flows of information § Decision points/basis not included © Virtual University of Pakistan

DFD-Symbols Dataflows: pipelines through which packets of information flow. Arrows are labeled with name of the data that moves through © Virtual University of Pakistan

DFD-Symbols Data Store ØRepositories of data in system ØStatic data ØData held for processing ØName is a noun phrase © Virtual University of Pakistan

DFD-Symbols Process transforms incoming data flow into outgoing data flow OR © Virtual University of Pakistan

DFD-Process ØNumbered ØName is verb/object phrase; ØNoun for high-level systems 1. 0 Process 1. 0 OR Process © Virtual University of Pakistan

DFD-Symbols External Entities ØSources/destinations for data ØOutside the system ØName is Noun Phrase © Virtual University of Pakistan

DFD-Symbols Collector ØSeveral data flows combine here ØNo processing occurs here © Virtual University of Pakistan

DFD-Symbols Separator ØSeveral data flows split from here ØNo processing © Virtual University of Pakistan

DFD-Symbols Ring-sum operator ØShows two possible data flows ØOnly one is followed © Virtual University of Pakistan

DFD-Symbols AND operator ØShows two data flows ØBoth are followed © Virtual University of Pakistan

Types of DFD ØContext diagram ØLevel 0 diagram ØDetailed diagram © Virtual University of Pakistan

Context Diagram ØConsists of single Process/System ØRepresents the system/process being analyzed ØName: Usually a Noun phrase © Virtual University of Pakistan

Context Diagram ØShow Context Only ØInputs/outputs ØExternal Entities ØNo Data Stores ØNo flows between external entities © Virtual University of Pakistan

Context Diagram © Virtual University of Pakistan

Context Diagram Student Dean Cla ss Sch Req ues edu ts le ferin f O e Cla un o C ss gs Admission System ts oa y. L t l u c Fa Cla ss L rs Cou ets e h d. S ata t. D n e d Stu ists Faculty Member Registrar © Virtual University of Pakistan

Diagram 0 Class Requests Student 2. 0 Produce Student Schedule Student Data Registrar Request Status 1. 0 Process Requests Old Class Data C Updated Class Data Class Registration Updated Student Data S Student Registration 3. 0 Create Student File Course Offering 4. 0 Create Class File 5. 0 Produce Class Lists Faculty member © Virtual University of Pakistan 6. 0 Produce Class Counts 7. 0 Produce Faculty Load Sheets Dean

That is all for lecture 5, however, Due to time available discussed Level 0 diagram in air, to be included Later insh. Allah © Virtual University of Pakistan

Student Dean Cla ss Sch Req ues edu le ferin f O e ts Cla un o C ss gs Admission System ts e h ad S o y. L t l u c Fa Cla ss L rs Cou ata t. D n e d Stu ists Faculty Member Registrar © Virtual University of Pakistan

Diagram 0 Class Requests Student 2. 0 Produce Student Schedule Student Data Registrar Invalid Request 1. 1 Process Requests Old Class Data C Updated Class Data Class Registration Updated Student Data S Student Registration 3. 0 Create Student File Course Offering 4. 0 Create Class File 5. 0 Produce Class Lists Faculty member © Virtual University of Pakistan 6. 0 Produce Class Counts 7. 0 Produce Faculty Load Sheets Dean

Detailed Diagram Class Registration s s a l C d l O ta Da Class Requests Student Rejected Request S Student Registration ed pt t ce es Ac qu Re Accepted Request Invalid Request 1. 2 1. 1 Check Edit Class Requests Valid Counts Requests 1. 3 Update Student © Virtual University of Pakistan Data Updated Class Data C 1. 4 Update Class Data

Overview ØContinue discussion on DFD ØDiscussion on Design Phase ØDatabase Design and Data Models © Virtual University of Pakistan