[DBMS] Unit 4- Conceptualize Design using the Entity Relationship (ER) Modeling

   ♦ The Entity Relationship (ER) model :

An entity relationship model, also called an entity-relationship (ER) diagram, is a graphical representation of entities and their relationships to each other, typically used in computing in regard to the organization of data within databases or information systems. An entity is a piece of data-an object or concept about which data is stored.

♦ Developing an ER Diagram.
An Entity Relationship Diagram (ERD) is a visual representation of different data using conventions that describe how these data are related to each other.

 

Fig:ER diagram example with entity having attributes

 ♦ Database Design Challenges:  Conflicting Goals:

Database designer often must make design compromises that are triggered by conflicting goals such as;

• Observance  to design standards

• Processing speed, and

• Information requirements

 

►Design Standards :
The database design must conform to design standards. Such standards have guided you in developing logical structures that minimize data redundancies. Without the design standards, it is nearly impossible to formulate a proper design process, to evaluate an existing design, or to trace the likely logical impart of changes in design.