Database Design Project: ER Diagram for Rental Properties

Desklib provides solved assignments and past papers to help students succeed.

ASSIGNMENT -1

Contents
Introduction......................................................................................................................................3
1. Entity-Relationship Diagram.......................................................................................................4
2. Assumptions................................................................................................................................4
References........................................................................................................................................7
Figure 1: Diagram............................................................................................................................4

Introduction
The given case study is about the rental properties on which the task is to create the ER diagram
regarding the scenario, in which proper entities and attributes need to design with their respective
relationships. Here, in the given file the entity-relationship diagram is given with some
assumptions and business rules that are provided here.

1. Entity-Relationship Diagram
Figure 1: Diagram
2. Assumptions
Here are some assumptions that are kept in mind while drawing:

1. The use of the primary key is there in almost every entity so that they can be identified
uniquely (Quang & Pham, 2015).
2. Entity Rental_Property is created as the entities Owners and Property were previously
having a many-to-many relationship so to eliminate this relationship Rental_Property is
created in order to show that it is a weak entity. The other two attributes named as
Property and Owner is the associative entities in this diagram.
3. Entity emp_type in entity External is the multi-valued attribute as it can perform different
tasks that include the electricians, plumbers and other such maintenance staffs are
included in this attribute (Coronel & Morris, 2016).
4. The weak entity does not have any primary key and it cannot be identified uniquely.
5. Both the Property and Rental_Property have a one-to-one relationship.
6. Entity Owner and Application also have a one-to-one relationship.
7. Owner_Id is the primary key in this owner table (Wang et al., 2017).
8. In the application entity, Application_Num is the primary key that will uniquely identify
the applications that the customer will fill and is supervised by the property_manager.
9. PM_ID is the primary key in the Property_Manager and as the application entity has a
one-to-many relationship with this entity so in application entity it is assigned as the
foreign key.
10. As Property_Manager supervise other managers and staff so the entity Property_Manager
is interconnected with Staff entity with a one-to-many relationship.
11. Staff table contains StaffID as its primary key and PM_ID as the foreign key as it is
taking reference from table Property_Manager.
12. Specialization is also shown in the ER diagram in the form of staff table and the staff
entity is divided in Worker entity and External entity. On collaboration the overall entity
is Staff.
13. Customer can buy multiple Rental_Property so the relationship among them is a one-to-
many relationship.
14. The owner can rent multiple properties so the Rental_Property can have a one-to-many
relationship with the Owner (Dunn & Nel, 2017).
15. The property manager will supervise multiple Application so they both have a one-to-
many relationship.

Conclusion
The overall case study is covered with the help of the ER diagram and the diagram is created by
using the draw.io whose image is attached to the file. All the relationships are given and
explained. There are some assumptions that need to create so these assumptions are explained in
the above part of the file.

References
 Dunn, C., & Nel, L. D. (2017). Entity Relationship Diagram Mapping.
 Wang, W., Indulska, M., Sadiq, S., & Weber, B. (2017, September). Effect of linked
rules on business process model understanding. In International conference on business
process management (pp. 200-215). Springer, Cham.
 Coronel, C., & Morris, S. (2016). Database systems: design, implementation, &
management. Cengage Learning.
 Quang, H., & Pham, T. (2015). Expressing a temporal entity-relationship model as a
traditional entity-relationship model. In Computational Collective Intelligence (pp. 483-
491). Springer, Cham.