Steps in Database Design

Steps in Database Design

 

Steps in Database Design

The process of database design is divided into different parts. It consists of a series of steps.They are 

  • Requirement Analysis
  • Conceptual Database Design (ER-Diagram)
  • Logical Database Design (Tables, Normalization etc)
  • Physical Database design (Table Indexing, Clustering etc)
Requirement Analysis

In this phase a detailed analysis of the requirement is done.The objective of this phase is to get a clear understanding of the requirements.Various information gathering methods for this purpose. Some of them are
  • Interview
  • Analyzing documents
  • Survey
  • Site visit
  • Joint Applications Design (JAD) and Joint Requirements Analysis (JRA)
  • Prototyping

Conceptual Database Design (Data Modeling)

The requirements analyzed in the previous step is converted into  conceptual model.
The Entity Relationship Model(ER Model) is used at the conceptual design stage of the database design.The Entity Relationship Diagram (ER Diagram) is used to represent this conceptual design. ER diagram consists of Entities, Attributes and Relationships.
 
Input for conceptual design step  :Requirements Analyzed in the previous step
 
Output of conceptual design step :ER Diagram
 
 Logical Database Design
 
Once the relationships and dependencies are identified the data can be arranged into logical structures and is mapped into database management system tables.That simply means the ER digram is converted to relational tables.
 
Each Entity corresponds to  a Table.
Attributes of entities corresponds to fields in relational tables.
 
Normalization is performed to make the relations in appropriate normal forms.
 
 
 Input for Logical Database Design step:
 ER Diagram from previous step
 
Output of Logical Database Design step:
Tables (in Relational Database Management Systems)
 
 
 
Physical Database Design
 
It deals with the physical implementation of the database in a database management system. It include the specification of data elements, data types, indexing etc. All these information are stored in the data dictionary .