RDBMS

INTRO TO RDBMS-OODBMS-ORDBMS

Seema Sirpal
Delhi University Computer Centre

Databases
Data - raw facts/details
DATABASE- A shared collection of logically related data (and a description of this data), designed to meet the organization needs of an organization
The Database Management System (DBMS)
- software that enables users to define, create and maintain the database and provides controlled access to the database

Why We Need DBMS
There is an information explosion in today’s society
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Need to keep accurate records

Advantages of using a DBMS fall into three main categories:
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Proper maintenance of the data
Providing access to the data
Maintaining security of the data

Requirements of a Database System
Efficiency
Efficiency

in the access to and modification of very large amounts of data
Resilience
Resilience

in the ability of data surviving hardware crashes and software errors without sustaining loss or becoming inconsistent
Access Control
Access Control

in the ability to permit simultaneous access of data by multiple users in a consistent manner and assuring only authorized access
Persistence
Persistence

the maintenance of data over long periods of time, independent of any programs that access the data

Traditional Approach
Applications developed in an ad-hoc and opportunistic manner
Data requirements for applications derived independently Data files developed for individual applications Application programs are data dependent

Files Dedicated to Application
Programs
reservation data overdue letters loan data

reservation program loan program overdue loans program reservation file loan file book file person file Database Approach
Centralization of information management
Data shared by different groups of users and application programs
Provision of multiple interfaces
Representation of complex relationships between data
Integrity