Database Management Systems (dbms)

A database is a group of related files

File 1
File 2
File 3
Database
Student database
Eg: Course file
Student name file
Marks file

What is a Database?

Data collection may be . . .

Electronically Collected
Manually Collected

Key Features of a database

The data is

• input (stored) only once
• Organized
• accessible

effectively and efficiently

Database Building Blocks

• File/Table

A collection of related records.

• Record

A record is a group of related fields.

• Field

Field represents an attribute, or a characteristic or a piece of information

Database Building Blocks..

Table
a Record
a Field

Database Management System (DBMS)

• The DBMS is a software package which allows a user to define, create, and maintain the database and provides controlled access to this database.
• The interface between users and data is provided by a database management system.

Eg: Oracle, MS SQL-Server, MS Access

MySQL, PostgreSQL

Overview of a DBMS

DBMS
Data-bases
Modify/
Retrieval
(Command)
Results
Admin
Users

Characteristics of Modern DBMS

• Query processing
• Transaction management
• Concurrency control
• Database recovery
• Database security and authorization
• Distributed databases

Advantages of using DBMS

• Data duplication and storage space wasting can be avoided
• Inconsistency can be avoided
• Data can be shared
• Unauthorized access can be restricted
• Recovery from failures

Disadvantages of using DBMS

• cost of extra hardware
• cost of entering data
• cost of training people to use DBMS
• cost of maintaining DBMS
• complex