Database 2 External Schema
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Transcript of Database 2 External Schema
February 23 , 2002 A K Ramani 1
RECAP
Role of Databases
Classification
Evolution of Databases
February 23 , 2002 A K Ramani 2
Aim– General steps in Design &
Development of Databases in context to information system Development process.
Objectives1. Understand Information System
Architecture2. Database Analysis, Design and
Implementation issues3. Design Example
DATABASE DEVELOPMENT PROCESS
February 23 , 2002 A K Ramani 3
Database development Starts with Enterprise Data Modeling (EDM)Steps in EDM
1. Review current system2. Analyse the business area to be supported3. Data requirement4. Plan DB Project (s)
EDM considers general contents of organizational databases. Overall pictureHowever, comprehensive architectural plan of IS development is essentialFeatures
• ISA can grow & expand (vision)• Impact of Technology• Flexible• Eye on standards
ENTERPRISE DATA MODELING
February 23 , 2002 A K Ramani 4
Planning
Budget
Overall direction of IT & decision
Priority areas
BENEFITS OF ISA
February 23 , 2002 A K Ramani 5
Data
Process (DFD, Models)
Network
People
Events & points in time (RTDB)
Reason for Events , Rules
KEY COMPONENTS OF ISA
February 23 , 2002 A K Ramani 6
February 23 , 2002 A K Ramani 7
A Data oriented methodology for development of information systems.
For engineering IS, approach the Top-down methodology is followed where integration of individual system components takes place
IS DEVELOPMENT
February 23 , 2002 A K Ramani 8
Planning : ISA, including EDM (results is an ISA)
Analysis : Conceptual Data Model & Logical data base
Design : Logical / Physical DB Implementation : DB definitions ,
Tables, Indexes , Codes
STEPS OF IS DEVELOPMENT
February 23 , 2002 A K Ramani 9
Goal : To support Business Strategies with IT 3 Steps
1. Identify strategic planning factors – to develop planning context and to link information systems plan to the strategic plan of the organization
• Goals : Growth Rate, Return on Investment ( ROI )……..
• Success Factors : Quality, On-time, Employee productivity…..
• Problem Areas : Competition, Maintenance of records….
IS PLANNING
February 23 , 2002 A K Ramani 10
2. Identify Corporate Planning objects – define the business scope
1. Organizational Units – Various departments
2. Locations – business places
3. Business Functions – business processes like product development
4. Entity Types : Categories of data about people, places & things managed by company
5. Information System : Application S/W & supporting procedures.
IS PLANNING
February 23 , 2002 A K Ramani 11
IS PLANNING
3. Develop Enterprise Model – consists of a functional breakdown , an enterprise data model and various planning matrices.
1. Functional Decomposition – breaking down description of system into finer and finer details, identify important components.
2. High level ER diagram3. Planning Matrices – A format for showing
interrelationships between data entities.– Functions Support Functions– Production Operation Scheduling, Fabrication,
Assembly– Material Management Material requirement planning – - Purchasing– - Receiving– Marketing - Market research– - Order
fulfillment– - Distribution
February 23 , 2002 A K Ramani 12
Develop Enterprise Model– Decompose business function
– Planning Matrixes (using ER)
Functional decomposition helps in simplify problems , identify important components.
Functions Support Functions
Production Operation Scheduling, Fabrication, Assembly
Material Management Material requirement planning
- Purchasing
- Receiving
Marketing - Market research
- Order fulfillment
- Distribution
February 23 , 2002 A K Ramani 13
Sample Planning Matrix – for Order Fulfillment– Identify 1 or more database (s) ,keeping in mind
Enterprise view
– Develop ER models,describe each entity,business rules
– Develop planning Matrixes,linking various components
X
Business Function
Business Planning
Material Manage
Finance & Accts
Cus
tom
er
Pro
duct
Invo
ice
Em
ploy
ee
Data/Entity
X X X
X X
X X X
PLANNING MATRIX
February 23 , 2002 A K Ramani 14
Advantages
– Identify Orphans : indicate which data entities are not used by any function or which functions do not use any entities
– Spot Missing Entities – Prioritize Development
PLANNING MATRIX
February 23 , 2002 A K Ramani 15
Types of Planning Matrices – Location to Function : which business functions
are performed at which business locations– Unit to Function : which business functions are
performed at which business units– Information System to Data Entity : explains
how each information system interacts with data entity
– Supporting Function to Data Entity : Identified which data are captured , used , updated or deleted within each function
– Information System to Objective : Shows which information system support which business objective
PLANNING MATRIX
February 23 , 2002 A K Ramani 16
Project Identification & selection
Project Initiation & Planning
Analysis
Logical Design
Physical Design
Implementation
Maintenance
Enterprise Model
Conceptual Data Model
DATABASE DEVELOPMENT PROCESS
Logical Data Base Design
Physical Design
Database Implementation
Database Maintenance
Database Development SDLC
February 23 , 2002 A K Ramani 17
In SDLC total specifications of IS is developed in piecesSteps may overlapEnterprise model– Data needed for each IS, general contents of Data
base Conceptual Data Modeling– Entities & Relationships– Detailed Data model (Data base Analyst)– Identifying all organizational data– Business relationship– Rules for data integrity– Model may require improvements – ER,EER…..
SDLC and DBMS APPROACH
February 23 , 2002 A K Ramani 18
Logical Database Design– Transform conceptual model Relations that are
specific to DBMS used– Transactions, reports,displays to be supported– What data are to be maintained in DB?– Several users views to be integrated – Normalization : Process of designing well
structured relations, avoid unnecessary duplication of data.
Physical DB Design– Identify programs to process transactions,
generate reports– Efficiency , Security– H/W, OS, Network
SDLC and DBMS APPROACH
February 23 , 2002 A K Ramani 19
Database Implementation– Create DB definition, Code, test,
populate
– SQL,VB, C
– Train, Document, backup
RAD
ProblemEarly Prototype
ImplementationProblem
Conceptual Data Model
Prototyping Logical Data Base
Code & Contents
Analyse, Improve
Revise
DBMS APPROACH
February 23 , 2002 A K Ramani 20
– Automated support to assist system Development process
– Draw data models using entity relationship
– Generate code• Database definition commands
DBMS• Compose SQL commands
– An information repository, which contains information needed to generate diagram, forms, reports.
CASE TOOLS
February 23 , 2002 A K Ramani 21
System Analyst Analyze BusinessData base Analyst Data base
ComponentUser NeedsProgrammer CodingDatabase Administrator Computer Architecture experts
Construct GANTT/PERT ChartsReview Points
Senior DB/System Analyst is LEADER
PROJECT DEVELOPMENT
February 23 , 2002 A K Ramani 22
Users ViewConceptual SchemaPhysical or Internal Schema
ANSI Architecture
User-1 User-2 User-n- - -
Conceptual Scheme
Internal Scheme
Physical DB
External Level
Conceptual Level
Internal Level
MODEL / VIEW OF DATABASES
February 23 , 2002 A K Ramani 23
Data Independence is achieved by Inter-level MappingQueries are translated between levels automaticallyConceptual schema is encapsulated (independent of Database Management Technology)Physical schema is also encapsulated (specs to allocate & manage secondary memory)
Develop Conceptual Schema
Develop User View
Physical Schema
CA Features Performance
Enterprise
Data Model
User
Needs
MODEL / VIEW OF DATABASES
February 23 , 2002 A K Ramani 24
Centralized DB System
Database
DBMS
DATABASES ARCHITECTURES
February 23 , 2002 A K Ramani 25
Data Manager
Transaction Manager D
B
Distributed DB System
DATABASES ARCHITECTURES
February 23 , 2002 A K Ramani 26
Client Server DB
Client : User System Interface & localized Data
Sever : Shared Data
CLIENT
CLIENT
SERVER
DB
DBMS
DATABASES ARCHITECTURES
February 23 , 2002 A K Ramani 27
Client Server (2 Tired)
• Thin Client / Fat Server• Fat Client / Thin Server
DB Server
Server
DATABASES ARCHITECTURES
February 23 , 2002 A K Ramani 28
Client Server (3 Tiered)
DB Server
Client (s)DATABASE
Dept. Server
(Application Server)
Organizational Server (Higher Level)
Merging or Data
DATABASES ARCHITECTURES
February 23 , 2002 A K Ramani 29
DB –Driven Web Applications
AdvantagesMulti –processingAdvantages of each computer platform (PCs, Servers)Mix Client Technologies (Thin Client)Processing close to data , reduces trafficOpen System Standards
DB Server
WEB+Application Server
Internet
DATABASES ARCHITECTURES
February 23 , 2002 A K Ramani 30
Summary
General steps in DB development
ISA, EDM
DB Architectures