Database Development Data Analysis: The Entity Relationship Powered by De. Sia. More 1
Entity Relationship (E-R) Model n n n 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 Powered by De. Sia. More 2
Entity Relationship (E-R) Model n n 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. Powered by De. Sia. More 3
Entity Relationship (E-R) Model n 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. Powered by De. Sia. More 4
Entity Relationship (E-R) Model n 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. Powered by De. Sia. More 5
Overview of Database Development n n 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. n n Requirement Analysis Logical/Conceptual Database Design Powered by De. Sia. More 6
Requirement analysis n The very first step in designing database application is to understand: n n 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. Powered by De. Sia. More 7
Requirement analysis n n n 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. Powered by De. Sia. More 8
Requirement analysis n n 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 Powered by De. Sia. More 9
Conceptual Database Design n n 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 De. Sia. More 10
Fundamentals of E-R Diagramming n n 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. Powered by De. Sia. More 11
Fundamentals of E-R Diagramming n 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. Powered by De. Sia. More 12
Entities n n 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. Powered by De. Sia. More 13
Entities n It can be a physical object such as: n 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. Powered by De. Sia. More 14
Entities n n n 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. Powered by De. Sia. More 15
Entities n Example: n n n 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. Powered by De. Sia. More 16
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