• Explain data model?

Explain why nevigation is simple relational data model than in hirarchical model

Using OSI reference model explain the data communication between two hosts?

Data is information.

A data model is a collection of concepts that can be used to describe the structure of a database and provides the necessary means to achieve this abstraction whereas structure of a database means the data types,relationships and constraints that should hold on the data.

Data model are divided into three different groups

they are

1)object based logical model

2)record based logical models

3)physical models

Types:

Entity-Relationship (E-R) Data Model

Object-Oriented Data Model

Physical Data Model

functional data model