ER Diagram answer is 6 but how?

Question

Answer 1

Answer: 6

Since there are three entity sets in the given model, three tables corresponding to each of these entity sets is mandatory as shown below:

Now, we need to find how many extra tables are needed to fulfill the relationships.

1. Manages: Which employee manages what department can be fulfilled by adding eid in Dept table as a foreign key linked to primary key eid in Emp. The eid (foreign key) in Dept will be the manager of the department. NO EXTRA TABLE.

2. Reports: Subordinate reports to supervisor can be fulfilled by adding descriptive attribute supervisor_id  to the Emp table as a foreign key to eid in Emp. The employee in Emp who has a supervisor_id is a sub-ordinate and reports to some employee. The employee in Emp who has supervisor_id as NULL is a manager and not subordinate. NO EXTRA TABLE.

3. Works: Which employees is work in which departments can be fulfilled by creating a separate table Works (employees, departments) grouping many employees together with many departments. Works has multivalued attributes employees and departments. 1 EXTRA TABLE.

4. Owns: Which department owns which project can be fulfilled by creating a separate table Owns (departments, projects) grouping many projects together with many departments. Owns has multivalued attributes departments and projects. 1 EXTRA TABLE.

5. Assign: Which employee is assigned which project can be fulfilled by creating a separate table Assign (employees, projects) grouping many projects together with many employees. Assign has multivalued attributes employees and projects. 1 EXTRA TABLE.

6. Leads: Which employee leads what project can be fulfilled by adding eid in Project table as a foreign key linked to primary key eid in Emp. The eid (foreign key) in Project will be the Project Lead of the project. NO EXTRA TABLE.

$\text{Minimum tables needed = 3(mandatory)+3 (extra)=6}$

Comments

I apologize but the answer is 5. I mistakenly wrote my answer in the question description

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@sanya_Singh 1 I also got the answer as 5 initially, changed it to 6 to match your answer thinking that I am making a mistake. Still, The basic thinking behind the answer will be the same, three mandatory tables for three entity sets. Further, extra tables for relationships. We have to reduce the relationships in order to get minimum extra tables (which will be 2 now I guess).

Emp, Dept and Project are mandatory tables. Think of which extra table you can reduce.

PS: I still think answer is 6.

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I too getting answer as 6