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Database Development

Data Analysis: The Entity Relationship

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Entity Relationship (E-R) Model

Data analysis aims at identifying data requirement of the real world model (System to be automated for business purpose).

One of the fundamental tools used in data analysis is E-R Diagrams

E-R Modeling is part of conceptual modeling in data analysis



Conceptual modeling involves building a model of the real world expressed in terms of of the data requirements established.

A conceptual model is a model of the real world expressed in terms of data requirements.



So by using ER model, a real world enterprise data can be described in terms of objects and their relationships and it is widely used to develop an initial database design.



It provides useful concepts that allow us to move from an informal description of what users want from their database to a more detailed, and precise, description that can be implemented in a DBMS.


Overview of Database Development

The database design and development process can be divided into number of steps.

The ER model is the most crucial step and is relevant to these steps of development. Requirement Analysis Logical/Conceptual Database Design


Requirement analysis

The very first step in designing database application is to understand: what data is to be stored in the database what application must be built on top of

it and what operations are most frequent

and subject to performance requirements. Understand what users want from the

database.


Requirement analysis It is an informal process that involves

discussions with user groups. It involves eliciting what users would

like to have stored in an information system.

In software engineering perspective is referred to as requirement elicitation and specification.


Requirement analysis

Designing a software solution depends on correct elicitation/data requirements.

In most software engineering paradigms, the process starts with a requirements elicitation, followed by a specification


Conceptual Database Design

The information gathered in the requirements analysis step is used to develop a high level description of the data to be stored in the database.

This is where the ER Model can be undertaken in your development process. Powered by DeSiaMore 10

Fundamentals of E-R Diagramming

The ER model/diagramming is one of the best-known tools for logical database design.

Within the database community it is considered to be a very natural and easy-to-understand way of conceptualizing the structure of a database.


Fundamentals of E-R Diagramming

In this E-R Model, a given universe of discourse is represented using an entity model: a model built up of entities, relationships and attributes.


Entities An entity can be defined as a thing

which an organisation recognises as being of an independent existence and which can be uniquely identified.

It is an aspect of the real world which can be distinguished from other aspects of the real world.


Entities

It can be a physical object such as:

a house or a car, an event such as a house sale or a car service, or a concept such as customer transaction or order.


Entities There is a real difference between

an entity and an entity-type.

An entity-type is a category.

An entity is an instance of a given entity type. There are usually many instances of an entity type.


Entities

Example: A student is an entity-type whereas

Juma is an instance of this entity-type.

Juma is an entity Because the term entity-type is some

what cumbersome, most people tend to use the term entity as synonym for this.


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