Database Modelling

Table of Contents

1. Requirements Modelling 1

1.1. Context Diagram – Current System 1

1.2. Diagram 0 DFD – Current System 2

1.3. System Requirements 3

1.3.1. Outputs 3

1.3.2. Inputs 4

1.3.3. Processes 4

1.3.4. Performance 5

1.3.5. Controls 5

1.4. Scalability Issues 6

1.5. Functional Decomposition Diagram 7

2. Data Modelling 8

2.1. Context Diagram – Proposed System 8

2.2. Diagram 0 DFD – Proposed System 9

2.3. Data Flows and Data Stores 10

2.4. Data Elements in Data Stores 12

1. Requirements Modelling

1.1. Context Diagram – Current System

Figure 1: Context Data Flow Diagram – Cornucopia College Housing System

Accommodation Providers must contact the College Housing office to advise them of their listing. The Accommodation Providers are not able to directly add their listings to the binders.

1.2. Diagram 0 DFD – Current System

Figure 2: Diagram 0 DFD – Cornucopia College Housing System

1.3. System Requirements

Explain system additions – landlord database, landlord add data – not at this stage as it requires authentication system

The preliminary investigation has identified several requirements for the new system. The features and characteristics that have been highlighted are that it must be:

• Easy to access;

• Tamper proof;

• Up to date;

• Easy to maintain.

The current binder system requires prospective tenants to visit the Cornucopia College Housing office and manually search through the binders. This does not make the system very accessible to people requiring accommodation that cannot attend the office. The current system is difficult for someone to filter out the listings that are not suitable for them. The new system should allow people to search for listings that suit their requirements.

During the investigation it was noted that unauthorised removal of listings occurs. Listings are removed from the binders by people seeking accommodation so that they reduce the competition for the desirable properties. The new system should only allow Cornucopia College Housing office staff to remove listings.

The current binder system may store a single listing in up to 15 different binders. When a listing is to be removed from the binders it is sometimes missed in one or more of the binders. This leads to an inconsistent system that contains incorrect information. The new system should store a listing once, thereby allowing for it to be removed from all searches and listings when it is rented.

The current hand-written listings are susceptible to error and the omission of important information. Maintaining the listings may require the alteration of 15 different forms which may result in additional errors and inconsistencies. Cornucopia College Housing office staff are required to search through all 15 binders each month to remove listings that are older than two months. The new system should allow the staff to enter the listing details once, using a process that validates the information provided. The system should automatically purge listings that are older than two months and provide the office staff with a report of these listings.

1.3.1. Outputs

The following outputs have been identified:

• Up to date listings;

• Restricted listings;

• Ordered listings;

• Searchable listings;

• Accessible via the Internet.

Achieving