Entity-relationship Model and Mountain View Community

Topics: Entity-relationship model, Entity, Unified Modeling Language Pages: 6 (1381 words) Published: March 10, 2011
Turgut TezirTEZIR-1
CS 504.2354
Mountain View Community Hospital

Project Case 3
Project Question:

1. Why would Mountain View Community Hospital want to use entity-relationship modeling to understand its data requirements? What other ways might the hospital want to model its information requirements?

This hospital wants to use E-R modeling to understand data requirements. E-R modeling is very easy to understand and shows all the business rules. • Entity-relationship modeling is logical representation of the data for an organization or for a business area. The E-R model is expressed in terms of entities in the business environment, the relationship among those entities, and attributes of both entities and their relationship. E-R model is normally expressed as entity-relationship diagram, which is graphical representation of the E-R model.

This Hospital also can use Object-Oriented model.
• (It is not recommended)Traditional File processing system, but there are lots of disadvantages with this using this system? Hospital can use information engineering, a top-down information systems planning approach.

2. Do there appear to be any weak entities in the description of the Mountain View Community Hospital data requirements? If so, what are they?

No weak entity. However, treatment can be a week entity.
• Treatement_ID
1. Threatment _Num
2. Threatment_Name

3. What is the significance in developing an E-R diagram for Mountain View Community Hospital to the third entry the preceding list, which states that some patients are assigned to a bed, but outpatient are not assigned to bed?

Some patient assigned to a bad, some of them don’t PATIENT has two subtypes • In Patient (has relationship between Bed)
• Out Patient

4. Is Mountain View Community Hospital itself an entity type in a data model to represent its data requirements?

No. We don’t need to model Hospital entity type.


1. Study the project description very closely. What other questions would you like to ask in order to better understand the data requirements at Mountain View Community Hospital? • Do we need to model the relationship with intern, volunteers and donors? • Do all Hospital workers nurses, staff, physicians and etc. are subtypes of Employee? • Do we need to record patient history?

2. Develop an E-R diagram for Mountain View Community Hospital. State any assumption you had to make in developing the diagram? [pic]

Note: I did some mistake in this diagram but I fixed it in second diagram.

3. The project description describes an entity type called Item. Given your answer to project exercise 2, will this entity type also be able to represent in-room TV’s as a billable items to patients? Why or why not?

No. The entity type Item has a Unit-Cost attribute.

4. Suppose the attribute bed number were a composite attribute, composed of care center ID, room number, and individual bed number. Redraw any part of your answer to project exercise 2 that would have change to handle this composite attribute.

5. Consider your new E-R diagram for Mountain View Community Hospital after changing your answer to Exercise 4. Now, additionally assume that a care center contains many rooms, and each room may contain items that are billed to patients assigned to that room. Redraw your E-R diagram to accommodate this new assumption.


6. Does your answer to project Exercise 2 allow more than one physician to perform a treatment on a patient at the same time? If not, redraw your answer to project Exercise 2 to accommodate this situation. Make any additional assumptions you consider necessary in order to represent this situation.

Yes. It allows more than one physician to perform a treatment on a patient at the same time.

7. does your answer project Exercise 2 allows the...
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