Data Models
What is data model?

Data model is a conceptual tool used to describe data and data relationships, data semantics and consistency constraints

What are the types of data models

A. Object based logical model

Example

Entity relationship model

B. Record based logical model

Examples

1. Hierarchical data model

Example for Record based data model – Hierarchical data model

2. Network data model

Example for Record based data model – Network data model

3. Relational data model

In relational data model, data exists in two dimensional tables known as relations. A relation (table) consists of unique attributes (columns) and tuples (rows).

Sometimes the value to be inserted into a particular cell will be unknown, or it will not have any value. This is represented by a null. Please note that null is not the same as zero, blank or an empty string

A database whose logical organization is based on relational data model is a Relational Database

A DBMS that manages the relational database is known as RDBMS

Example for Record based data model – Relational data model

Example for Record based data model – Relational data model

 
 
 
 
Comments(0) Sign in (optional)
 
Add a new comment...  (Use Discussion Board for posting new aptitude questions.)

Name:
Email: (optional)
3 + 8 = (please answer the simple math question)

Post Your Comment
X  
View & Edit Profile Sign out
X
Sign in
Google
Facebook
Twitter
Yahoo
LinkedIn
X