ER diagram have include all tables & all attributes or not?

Question

1. all the attributes include in ER diagram or not?
2. My database have 8 tables and nearly 50 attributes, i include these 50 attributes in a single diagram OR not?

Answer 1

First thing - ER diagram is something that is first created usually and then later on converted into a data model like relational. So the data storing requirements are modeled into an ER diagram first and later on are converted into tables. There is rarely a case where you have to reverse engineer an existing data model into the ER diagram level (Conceptual Level).

During this process, tables are created for enitities and relationships accordingly (using some algorithmic process).

And a good way of practice is to draw the ER diagram with only entities and relationships without the attributes as it makes it very clumsy and difficult to concentrate on the actual entities and the relationships between them. Later on in a separate document or a page, you can list all the attributes corresponding to entities individually.

Hope this gives you a basic idea.