1.Database Management System (DBMS)

Database Management System (DBMS)

            Data is very important to a company. So it should be stored and maintained accurately. Also the data can be accessed very quickly. For this purpose we can use DBMS. DBMS is a system that is used to store and manage data. We can store and manipulate the data. Manipulation of data includes

1.    Adding new data

2.    Changing existing data

3.    Deleting the existing data

A DBMS provides various functions like data security, data integrity, data sharing, data concurrence, data independence, data recovery etc

Main Features of DBMS are

·         Support for large amount of data

·         Data sharing, concurrency and locking

·         Data Security

·         Data Integrity

·         Fault tolerance and recovery

·         Support for Languages

Entity and Attribute

Any object stored in database is known as an Entity. Each Entity is associated with a collection of attributes.

 Eg: In the case of an organization   ,   employee is an entity and employee code, department, designation etc are attributes.

The relationship between entities may be one to one, many to one, and many to many..

Data Models

It describes the way of storing and retrieving the data. Three different types of data models are  

·         Hierarchical –The data is stores in the form of a tree.. There is a parent child relationship.

·         Network – In this model, data is stored along with the pointers. This pointers specify the relationship between the entities.

Relational – in this model, the data is stored as tables. There is a collection of rows and columns