You work as a Database Designer for Allen Inc. You are designing the database of a company that has
several divisions (e.g. Spare Parts division). Each division has several departments (e.g. Quality
Control department), and every department has several employees. What will be the relationship
between the two entities, namely, division and employee, if you model the database?

A.
No direct relationship

B.
One-to-one

C.
Many-to-many

D.
One-to-many

Explanation:
There is no direct relationship between the two entities: division and employee. In the given
scenario, the relationship is as follows: There exists a one-to-many relationship between division and
department. There exists a one-to-many relationship between department and employee.
Answer B is incorrect. In a one-to-one relationship, every instance of the first entity has only one
instance of the second entity. For example, in an organization, every department such as Sales has
only one Senior Manager, and all the other employees in the Sales department work under him. This
relationship between the Sales department and the Senior Manager is one-to-one.
Answer D is incorrect. In a one-to-many relationship, every instance of the first entity can have
more than one instance of the second entity, but for the instance of the second entity, there is
exactly one instance of the first entity. For example, the relationship between Department and
Employee is one-to-many. There are many employees working in a department (e.g. Sales).
Answer C is incorrect. In a many-to-many relationship, every instance of the first entity can have
multiple instances of the second entity, and every instance of the second entity can also have more
than one instance of the first entity. For example, a customer can purchase more than one product,
and a product can also be sold to several customers.