Specified during the database design process

Not expected to change frequently

data model :a collection of concepts that can be used to describe the structure of a database

The structure of a database mean the data types, relationships, and constraints

was developed by IBM and North American Rockwell known as Information Management System.

This model is the first DBMS model

It represents data as relations or tables

Object Model :It replaces the hierarchical tree with a graph.

It uses pointer to navigate between the stored data.

It represents the data as record types and one-to-many relationship

It is used in File Management System.

It is easy to maintain and modify the existing code.

It is used by people who don't know how database is implemented.

It does not describe cardinality

It consists of components like domain, attributes, tuples.

Some of the popular Language and Notations used:
• Chen
• UML • Crow's foot • Bachman and others.

Defines both schemas.

Allows retrieval, insertion, deletion, modification

Database management systems can be classified based on several criteria,such as the data model, user numbers and database distribution.

Centralized, Distributed

It can be a single-user database system, which supports one user at a time, or a multiuser
database system,