Database Definition For Beginners

Definitions
Database:
organized collection of logically related data
Data:
stored representations of meaningful objects and events
Structured:
numbers, text, dates
Unstructured:
images, video, documents
Information:
data processed to increase knowledge in the person using the data
Metadata:
data that describes the properties and context of user data

Data in context

Summarized data

Disadvantages of File Processing
Program-Data Dependence
All programs maintain metadata for each file they use
Duplication of Data
Different systems/programs have separate copies of the same data
Limited Data Sharing
No centralized control of data
Lengthy Development Times
Programmers must design their own file formats
Excessive Program Maintenance
80% of information systems budget

Problems with Data Dependency 1) Each application programmer must maintain his/her own data
2) Each application program needs to include code for the metadata of each file
3) Each application program must have its own processing routines for reading, inserting, updating, and deleting data
4) Lack of coordination and central control
5) Non-standard file formats

Problems with Data Redundancy
1) Waste of space to have duplicate data
2) Causes more maintenance headaches
3) The biggest problem:
Data changes in one file could cause inconsistencies
Compromises in data integrity

SOLUTION: The DATABASE Approach
1) Central repository of shared data
2) Data is managed by a controlling agent
3) Stored in a standardized, convenient form

Advantages of the Database Approach
1) Improved data consistency
2) Improved data sharing
3) Increased application development productivity
4) Enforcement of standards
5) Improved data quality
6) Improved data accessibility and responsiveness
7) Reduced program maintenance
8) Improved decision support

Costs and Risks of the Database Approach
1) New, specialized personnel
2) Installation and management cost and complexity
3) Conversion costs
4) Need for explicit backup and recovery
5) Organizational conflict

Elements of the Database Approach
Data models
Graphical system capturing nature and relationship of data
Enterprise Data Model–high-level entities and relationships for the organization
Project Data Model–more detailed view, matching data structure in database or data warehouse
Relational Databases Database technology involving tables (relations) representing entities and primary/foreign keys representing relationships
Use of Internet Technology Networks and telecommunications, distributed databases, client-server, and 3-tier architectures
Database Applications Application programs used to perform database activities (create, read, update, and delete) for database users

Components of the Database Environment
CASE Tools
–computer-aided software engineering
Repository
–centralized storehouse of metadata
Database Management System (DBMS)
–software for managing the database
Database
–storehouse of the data
Application Programs
–software using the data
User Interface
–text and graphical displays to users
Data/Database Administrators
–personnel responsible for maintaining the database
System Developers
–personnel responsible for designing databases and software
End Users
–people who use the applications and databases

The Range of Database Applications
1)Personal databases
2)Workgroup databases
3)Departmental/divisional databases
4)Enterprise database

Enterprise Database Applications
1)Enterprise Resource Planning (ERP)
Integrate all enterprise functions (manufacturing, finance, sales, marketing, inventory, accounting, human resources)
2)Data Warehouse
Integrated decision support system derived from various operational databases