Entity Relationship Model

Entity Relationship Model

                    The ER model defines the conceptual view of a database. The ER model is considered a good option for designing databases.
Entity:

           An entity is an existing or real thing. For example, in a school database, students, teachers, classes, and courses offered can be considered as entities.

           An entity set is a collection of similar types of entities. An entity set may contain entities with attribute sharing similar values. For example, a Students set may contain all the students of a school; likewise a Teachers set may contain all the teachers of a school from all faculties. 

           It is relatively easy to understand, and hence, the most widely used one in designing a database. 

Advantages

1. Straightforward relation representation: Having designed an E-R diagram for a database application, the relational representation of the database model becomes relatively straightforward.
2. Easy conversion for E-R to other data model: Conversion from E-R diagram to a network or hierarchical data model can· easily be accomplished.
3. Graphical representation for better understanding: An E-R model gives graphical and diagrammatical representation of various entities, its attributes and relationships between entities. This is turn helps in the clear understanding of the data structure and in minimizing redundancy and other problems.