Data model
This presentation is the property of its rightful owner.
Sponsored Links
1 / 18

Data Model PowerPoint PPT Presentation


  • 207 Views
  • Uploaded on
  • Presentation posted in: General

Data Model. Different types of data model. Entity – Relationship (E-R) Model. Relational Model Object –Based Data Model Semi structured Data Model Network Model Hierarchical data model. The Entity Relationship Model. ER Model consists of a collection of basic objects called entities

Download Presentation

Data Model

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Data model

Data Model


Different types of data model

Different types of data model

  • Entity – Relationship (E-R) Model.

  • Relational Model

  • Object –Based Data Model

  • Semi structured Data Model

  • Network Model

  • Hierarchical data model


The entity relationship model

The Entity Relationship Model

  • ER Model consists of a collection of basic objects called entities

  • Relationships among these objects.


Relational model

Relational Model

  • The relational model uses a collection of tables to represent both data and the relationships among those data.

  • It is record based model

  • Each table contains records ( fields or attributes)


Relational model cont

Relational Model (cont…)

  • Advantage :

    • Structure independence

    • Conceptual (Theoretical) Simplicity

    • A powerful database management system

  • Disadvantage

    • Transaction Process is not efficient

    • Processing time is low


Object based data model

Object –Based Data Model

  • The object oriented model can be seen as extending the E-R model with notions of encapsulation methods (functions) and object identity.


Object based data model cont

Object –Based Data Model (cont…)

  • Advantage :

    • Exceptional conceptual simplicity

    • Visual representation

    • Effective communication tool

    • Integrated with the relational database model

  • Disadvantage

    • Limited constraint representation

    • Limited relationship representation

    • No data manipulation language

    • Loss of information content


Semi structured data model

Semi structured data model

  • The semi structure data model permits the specification of data where individual data items of the same type have different set of attributes.

  • Example

    • XML ( Extensible Markup Language)


Network model

Network Model

  • It is data structure diagram

  • Advantage

    • Data independence

    • Conceptual simplicity

    • Easy to design

  • Disadvantage

    • Lack of structure independence


Hierarchical model

Hierarchical Model

  • It uses tree structure diagram

  • Advantage

    • Simple

    • Easy to update

    • Design is simple

    • Database security

    • Efficiency

  • Disadvantage

    • Implementation complexity

    • Difficult to manage


Database languages

Database Languages


Database languages1

Database Languages

  • A database system provides two different types of languages.

    They are

  • Data Definition Language

    • To specify the database schema

  • Data Manipulation Language

    • To express database queries and updates


Data definition language

Data Definition Language

  • Specifies the databaseschema by a set of definitions

  • Result of compilation of DDL statements is a set of tables that is stored in a special file called data dictionary.


Data model

  • Data dictionary

    • A data dictionary is a file that contains metadata (that is data about data).

    • This file is consulted before actual data are read or modified in the database system.

  • Active data dictionary

    • Created and maintained automatically by the DBMS

  • Passive Data dictionary

    • Managed by users used more during design and development stage


Data dictionary should contain information about

Data dictionary should contain information about

  • Data structures and types of data

  • Domain information about each attribute (columns)

  • Their relation to other entities (Require a user to specify what data are needed from tables)

  • Documentary and technical information regarding systems and design features.

  • Access Control information

  • Details of logic structures that are mapped into the database

  • Resource usage detail


The data values stored in the database must satisfy certain consistency constraints

The data values stored in the database must satisfy certain consistency constraints

  • Domain constraints

    • Example

    • Integer types, character types, date and time types.

  • Referential Integrity

    • Refer another table or attribute

    • Min balance Rs 1000

  • Authorization

    • Permit access (read, insert, update, delete)


Data manipulation language dml

Data Manipulation Language (DML)

  • DML is a language that enables users to access or manipulate data as organized by the appropriate data model.

    • Retrieval of information stored in the database.

    • Insertion of new information

    • Deletion of information

    • Modification of information

      • DML

        • Procedural

        • Non procedural (Declarative)


Data model

  • Procedural DMLs

    • Require a user to specify what data are needed and how to get those data.

  • Non Procedural DMLs

    • Require a user to specify what data are needed without specifying how to get those data.


  • Login