Question

Part 1:

Why do we need to create an E-ER model for an ER model?

Explain the ‘overlap’ and ‘disjoint’ rules of E-ER model

Part 2:

You are creating a database for a college/university. Develop an E-ER Model with this given

information:

1)

Two specializations of Person: employee, student



Person can be employee and/or student at the same time

2)

Three specializations of Employee: staff, faculty, student assistant

3)

Two specializations of Student:



Graduate, undergraduate student



Student assistant

Student can ONLY be graduate or undergraduate student, not both at the same time

4)

Two specializations of Student assistant: teaching assistant, research assistant



Student assistant can only be teaching or research assistant at the same time, not both

Details required:



You should show 5 attributes of person, at minimum



You should have at least one unique attribute for each subtype entity



Clearly show applied ‘Overlap’ and ‘disjoint’ rules

E-ERD:

Answer 1

Part 1:

we need to create ER model for the above statement is because with the help of the ER model we can simply provide a visual starting point for our database and we can create the blueprint for the database project.

This ER Diagram is useful For organizing the data in a certain specific format and that can be represented by the specific structure.

It can also be used for integrating our own data into pre-existing data.

OVERLAP RULE:

The Overlap rule is the statement that forces a subclass and that having the set of overlapping entitles.

It is also having the overlapping subtypes and that contain nonunique subsets of the super-entity set.

Disjoint Rule:

The Disjoint Rule is the rule that forces subclasses to have the Disjoint-set of entity sets.

It does not belong to any of the subclasses of the disjoint rule.

We can represent it in a single line.

Part 2:

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