Wednesday, 24 July 2019

ER Diagram in DBMS | What are the steps to construct ER Diagram

Entity Relational model or ER model is a high level conceptual data model developed by peter Chen in 1976 to facilitate database design. Conceptual modeling is an important phase in designing a successful database. A conceptual data model is a set of concepts that describe the structure of a database and associated retrieval and updation transactions on the database. The ER model is the generalization of the earlier available commercial models like the Hierarchical and the Network model.

Feature of the ER Model

  1. The ER diagram used for representing ER model can be easily converted into tables in the relational model
  2. The ER model is used for the purpose of good database design by the database developer so to use that data model in various DBMS.
  3. It is helpful as a problem description tool as it shows the entities and the relationship between those entities.
  4. It is very simple and easy to understand by various types of users and designers because specific standards are used for their representation.

  5. It provides an easily understood pictorial map for the database design.
  6. It is a top down approach to database design.
  7. It offers an effective framework for integrating multiple applications.
  8. It gives precise understanding of the nature of data and how it is used by an organization.

What are the steps to construct ER Diagram

Below points show how to go about creating an ER diagram.
  1. Identify all the entities in the system. An entity should appear only once in a particular diagram. Create rectangles for all entities and name them properly.
  2. Identify relationships between entities. Connect them using a line and add a diamond in the middle describing the relationship.
  3. Add attributes for entities. Give meaningful attribute names so they can be understood easily


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