Definitions

Data - Facts, text, graphics, images, sound, and video segments that have meaning in the users’ environment

Information - Data that have been processed in such a way as to increase the knowledge of the person who uses the data

Metadata - Data that describe the properties or characteristics of other data

Database - A computerized orderly collection of logically related data
 
5 types of databases (Table 1-4)

  • Personal - support one user
  • Workgroup - support < 25 users
  • Department - support a functional unit within a company
  • Enterprise - support the entire organization
  • Internet - universal access

Components of a database system (Fig. 1-11)

Data

Data definitions

Data occurrences

Users

Data administrators

System developers

End users

Software

CASE tool

DBMS

Application programs

User interface

Hardware

Storage or Repository

Processor

Traditional file processing (Table 1-2)

  • Data dependence
  • Data duplication/redundancy
  • Data isolation
  • Data incompatibility
  • Data inconsistency

Database processing (Table 1-5)

  • Data independence
  • Data sharing
  • Data consistency
  • Data standardization
  • Data accessibility
  • Data security??

Milestones in database processing (Fig. 1-12) 

Era

Milestone

Contributions

1960s

 

Organizational transaction processing
  • Data volume 
  • Data standard

1970s

 

Hierarchical (IMS) & Network (IDS) database model
  • Concurrency 
  • Efficiency 
  • Reliability

1980s

 

Relational database model
  • PCs 
  • Popularity 
  • Intuitive
  • Ease of use

Mid 1980s

Client-Server database
  • Connectivity

Late 1980s

Distributed databases
  • Flexibility

Early 1990s

Object-oriented database
  • Reusability

1990s

Multimedia/Network databases
  • Accessibility 
  • Pictures, sounds, movies, animations

 

Database analysis & design/development-- specifying a comprehensive organizational database structure to provide flexible, timely, and secure access to the right data so as to enhance organizational productivity

Evolution of database analysis & design

  • Function-drive approach -- focusing on activities performed within an organization (information requests consolidating)
  • Data-driven approach -- focusing on data and their properties (information needs understanding)
  • Strategy-driven approach -- focusing on aligning information technology with business strategies (strategic data planning)

Phases in strategic data planning (Table 2-1)  

Phases

Goal

Elements

Strategic factor identification

(Table 2-2)

To develop a context for database development
  • goals 
  • critical success factors 
  • problem areas

Corporate object identification

(Table 2-3)

To define the scope for database development
  • organizational units 
  • organizational locations 
  • business functions 
  • data categories 
  • data handling procedures and applications

Enterprise model development

 

To create an overall picture/explanation of organizational data
  • functional decomposition for each business function (Fig. 2-2) 
  • enterprise data model (Fig. 2-1) 
  • planning matrixes (Fig. 2-3)

Database development strategy  

Strategy

Description

Strength

Top-down

general à specific

  • Strategic goals 
  • Information requirements 
  • System needs

·  Global perspective 

·  Consistency 

·  Maintainability


 

Bottom-up

specific à general

  • System needs 
  • Requirement specifications

·  Fast 

·  Less risky


 

 Database development activities (Figure 2-5)

  • Enterprise modeling à need? scope?
  • Conceptual modeling à general understanding of database requirements
  • Logical design à well structured data specifications
  • Physical design à programs, hardware, operating systems, network, access mechanism, etc.
  • Implementation à write, test, install database processing programs
  • Maintenance à meet changing business conditions, correct errors, improve processing speed, ...

Outputs from database development 

Database schema
  • conceptual 
  • external/user view 
  • physical/internal

Database applications
  • forms 
  • queries 
  • reports 
  • menus 
  • programs