Physical Data Flow Diagram- Aberdare Dentist scenario



Physical Data Flow Diagram- Aberdare Dentist scenario

Task 1

A physical DFD of a current system is often created first because this is what users are most comfortable with. They usually know how data moves around the system by linking it to people or places.

Task 2

Dentist

When a patient comes to you he will give you his Patient Record Card. You should pretend to give the patient some kind of treatment and at the end, pretend to mark his/her card with the treatment carried out and give it back to the patient who will take the card to the receptionist.

Receptionist

Current patients book appointments through the receptionist. The appointments are logged in a page a day diary. Each morning you check the dentist's appointment diary. For each appointment that day the Patient Record Cards are retrieved. You will have record cards ready for when the patients arrive. When a patient with an appointment arrives, you give the patient his/her record card and send them into to see the dentist, When the patient comes out again, you take the card, tell the patient how much it costs, pretend to take some money and give the patient a receipt. You repeat this for the next patient. When a new patient arrives you ask a series of questions (as on the Patient Record Card) and pretend to fill in the details the patient gives you. You then pretend to make a booking for the patient and send him/her away.

Existing patient

You have booked an appointment and need to go to the receptionist and say who you are. You will be given your Patient Record Card to present to the dentist. When the treatment is over, you need to take your card back to the receptionist and pay for your treatment. You will be given a receipt.

New patient

New patients are asked a series of questions when they join a dental practice. You will be asked your name, address, GP's name and surgery, any medication you are currently taking and any allergy details or general health concerns. You should give these to the receptionist when you arrive.

Task 3

Task 4

There are at least four categories of things that cannot adequately be described in data models:

Implied assumptions

When Optional relationships are activated

How to keep multiple paths between entities consistent

Derivations

The leaves of Entity Life History trees are referred to as effect boxes, because they represent the eventsby which the entity is effected. The name of an event box need not have any special format but shouldaccurately describe the event. Events must have occurred for the entity to be changed so the names of events should always involve a verb in the past tense.

If an event does not create, modify or delete an instance of an entity then it should not be shown on thediagram (or the entity lacks attributes that the event should modify and some more analysis and re-modelling is required).Each event should only be appear once on a given life history ...