Conceptual Database Model of Joanne Myers Apartments

This report provides a conceptual database model of the Joanne Myers Apartments database, including business rules, entity relationship diagram, and summary. The business rules were derived from the case study provided, and an entity relationship diagram was created using Microsoft Visio. The limitations and assumptions made during the design process are also discussed.

COVER PAGE

Contents
1 Discussion.................................................................................................................................................3
2 Business rules...........................................................................................................................................3
3 Entity relationship diagram......................................................................................................................6
4 Summary..................................................................................................................................................6

1 Discussion
The solution provided in this report is conceptual database model of the Joanne Myers Apartments
database and the steps that have been followed in order to arrive at the final design. The first step is to
identify the business rules y thoroughly analyzing the case study provided in the document. From the
business rules an entity relationship is drawn using Microsoft Visio to show the entities and their
attributes and all the different types of relationships that exist between the entities. A discussion of the
justification and any assumptions made is presented on the last section.
While modelling the database no problem was experienced as my analysis of the case study provided all
the information I needed to complete the task
2 Business rules
Based on the case study, the following are the business rules derived;
Entity: BUILDING
A BULIDING has one or more APARTMENT
A BUILDING is managed by one LESSEE.
Entity: LEASE
A LEASE can be signed by one or more LESSEE
A LEASE is for one APARTMENT
Entity: APARTMENT
An APARTMENT belongs to only one COMPLEX
An APARTMENT has one and only one LEASE at a time
An APARTMENT is assigned to one or more PARTKING_LOT
An APARTMENT can have one or more MAINTENANCE_JOB
AN APARTMENT has one or more PREINSTALLED_EQUIPMENT
Entity: KEY
A KEY results to one or more KEY_ALLOCATION records
Entity: PARKING_LOT
A PARKING_LOT is associated with one and only one APARTMENT
A PARKING_LOT belongs to only one building COMPLEX.
Entity: LOCKUP_GARAGE

A LOCKUP_GARAGE is associated with one and only APARTMENT
Entity: MAINTENANCE_JOB
A MAINTENANC_JOB is done for one and only one APARTMENT
A MAINTEANCE_JOB is associated with one and only one MAINTENANCE_COMPANY
Entity: MAITENANCE_COMPANY
A MAINTENANCE_COMPANY is associated with zero or more MAINTENANCE_JOBS
Entity: LESSEE
A LESSEE signs one and only one LEASE
A LESSEE makes one or more than one RENT_PAYMENTS
A LESSEE is gets one or more KEYS
A LESSEE can make zero or many RENTALS
Entity: PREISNTALLED_EQUIPMENT
A PREINSTALLED_EQUIMENT is assigned to one and only one APARTMENT
Entity: RENTAL
A RENTAL is associated with one and only RENTAL_EQUIPMENT
Entity: RENT PAYMENT
A RENT_PAYMENT is associated by one and only one LESSEE
Entity: RENTAL_EQUIPMENT
A RENTAL_EQUIPMENT is associated with zero or many RENTAL

3 ERD
Figure 1: Entity relationship diagram
4 Summary
This section discusses major justifications, assumptions and limitations related to the design of the
Joanne Myers Apartments.
All the relationships that shown in figure 1 above have been derived based on the business rules
discussed in section 2. According to Crow’s Foot database notation, the entity relationship diagram
shows the cardinalities and the optionality for every relation.

Its assumed that there are a few lockup garages in some of the complexes and these garages do not act
as parking spaces. An apartment that is assigned parking lot can also be allocated a lockup garage if it
falls under those apartments that can receive a lockup garage.
While modelling the database a special case was realized whereby to maintain data consistency a
manager of a complex is supposed to sign a lease like other tenants so that he can become the manager
of that complex because a manager of a complex has to be a tenant in an apartment belonging to the
complex.