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How to Draw ER Diagrams?

How to Draw ER Diagrams?

by Anamul Hauque -
Number of replies: 2

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.

Sounds simple right? In a complex system, it can be a nightmare to identify relationships. This is something you’ll perfect only with practice.


In reply to Anamul Hauque

Re: How to Draw ER Diagrams?

by Abir Mahmud -
ER diagrams can be mapped to relational schema, that is, it is possible to create relational schema using ER diagram.
...
Mapping Process
Create table for weak entity set.
Add all its attributes to table as field.
Add the primary key of identifying entity set.
Declare all foreign key constraints.
In reply to Anamul Hauque

Re: How to Draw ER Diagrams?

by Sweety Islam -

  1. Identify all the entities in the system. An entity should appear only once in a particular diagram. ...
  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.