Transcript Slide 1

Database Development
Data Analysis: The Entity
Relationship
Entity Relationship (E-R)
Model
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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
Entity Relationship (E-R)
Model
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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.
Entity Relationship (E-R)
Model
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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.
Entity Relationship (E-R)
Model
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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
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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.
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Requirement Analysis
Logical/Conceptual Database Design
Requirement analysis
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The very first step in designing
database application is to understand:
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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
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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
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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
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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.
Fundamentals of E-R
Diagramming
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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
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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
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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
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It can be a physical object such as:
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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
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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
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Example:
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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.