What is a database

1
What is a database?

• A database is data stored in automated form. It
  contains information about entities and
  relationships amongst entities
• A physical database is a representation of
  entities on storage media
• A logical database is a representation of
  entities independently of how the data is
  actually stored and represented

2
Data management
consists of all the activities needed to
ensure high quality data is available

• Objectives
• resilient
• adaptable

• Responsibilities
• representation, storage and organization
• manipulation and presentation
• protecting data

3
A DBMS

• A DBMS is a tool (s/w and sometimes h/w) for
  aiding effective data management

Application Program 1
Application Program 2
User 1
User 2
DBMS
Physical Database
4
A DBMS can ...

• Define data and their interrelationships
• Document data definitions and structures
• Represent, organize and store data
• Interface congenially with users
• Protect data
• Separate logical and physical concerns - data
  independence
• Provide data sharing

5
A DBMS will ...

• Improve data quality
• Improve performance
• Efficiency - utilisation of physical computer
  resources
• Effectiveness - how well the system meets user
  needs

6
Limitations of DBMSs

• A DBMS is a tool for aiding effective data
  management
• A DBMS cannot
• find the causes of poor quality data
• reconcile data authorization
• decide who needs which data
• design databases