Database Models in DBMS

DBMS: Database Management System

DBMS

• 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

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

    2. Network Model:

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

• 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.

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