Conceptual Design - This is a high level description of the structure of a database
Eg: E-R Diagram - Concise description of the data requirements of the users and includes detailed description of the data, relationship and constraints.
Logical Design This is the process of mapping the database structure developed in the previous phase to a particular database model. Physical Design This is the process of defining structure that enables the database to be queried in an efficient manner Eg: index and hash file design
Requirements collection & analysis
Conceptual Design
Logical Design
Physical Design
Database Requirements
Conceptual Data Model
Logical Data Model
Physical Data Model
Problem
Database Implementation
Entity – Relationship Modeling ER model is high level conceptual data model - Entity
- An entity is a thing in the real world with an independent existence .
- As entity may be an object with a physical existence . e.g. : a person , a student , a house, etc.
- An entity is any object that is relevant to the organization.
- Tangible object
- Intangible objects
- Events
Entities
Conceptual Design
Department
Employee
Project
Dependent
The Concepts of the ER Model - Attribute
- Each entity has particular properties or features (characteristics ) called attributes .
- e.g.
student entity(student no, name, address, dob) - Simple (atomic) attribute
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