Database Models in DBMS

DBMS: Database Management System

Database Management System

  • It is a collection of interrelated data and set of programs to access the data from database.
  • It is a suit of software programs for creating maintaining the data in the database.
  • Users are connected with DBMS not with the data.
  • It allows the organisation to store data in one location from which multiple users can access the data.
  • user can insert, update, delete the data by using tools provided by DBMS.
Different Database Models
    1. Hierarchical Model
    2. Network Model
    3. Relational Model
  1. Hierarchical Model:
For example think s1,s2 and s3 are the stores and p1, p2 and p3 are the parts.
Hierarchical model database
Hierarchical Model

  • Data is organised in the form of a tree structure.
  • Drawback is data redundancy and wastage of memory.
    2. Network Model:

Network model database
Network Model
  • The drawback in hierarchical model is rectified.
  • No data redundancy and no wastage of memory.
  • Drawback is no guarantee or the access of data
    3. Relational Model:
Relational model database
Relational Model
  • It uses the collection of tables to represent the data and to establish the relation among the data.
  • Tables are linked logically.
  • Data is stored in the form of tables.
  • The intersection of row and column will give one value.
  • High security for the data.
  • Data redundancy is less
  • It supports any type of data like numeric, char, date binary etc.
  • It supports NULL values.
  • It supports integrity constraints.
  • Multiple users can access the data from any location.
  • No physical link among the data.
  • Relationships established logically.
RDBMS: Based on relational model is called Relational Database. It is suit of software program for creating, maintaining and manipulating the data in relational database.

Ex: Oracle, SQL Server etc.

Oracle can run on any platform while SQL Server runs only on windows.

Back to SQL Tutorial Index                                        Next-->Dependencies

No comments:

Post a Comment