Programmers Stack Exchange is a question and answer site for professional programmers interested in conceptual questions about software development. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I felt this is the best place to ask this, rather than Stackoverflow as it is not related to programming.
Ok. The thing is I need to draw an ERD of a leave management system. Suppose there are three level of user roles there - Level A, B and C.
Where A can manage both B and C; B can manage only C and C is normal users.. Now I've specified an entity named USER in the ERD and thus have to maintain only one table in my database for all type of users and set a role flag and code according to that. But how exactly do I represent this three levels of users in an ERD, as the ERD has only one entity for USER? and role is just an attribute there?
Do I have to make three entities for three types of users and hence create three tables and continue like that? But I can manage all the functionalities with just one table and one flag.
Am a bit confused. Please do guide me. :)

share|improve this question
up vote 2 down vote accepted

You said it yourself, and gave it a good thought. Entity Relation Diagram. You have only one Entity of USER, thus you only need to put it once. Role is an attribute of that Entity.

I would digg deeper in the levels of roles in a Functional Diagram, where the Entities are used in a certain Functionality.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.