Question

Using your study of chapter 8 of Modern Systems Analysis and Design and class lecture, solve the following problem. In a real estate database, there is an entity called PROPERTY, which is a property for sale by the agency. Each time a potential property buyer makes a purchase offer on a property, the agency records the date, offering price, and name of the person making the offer.

1.Represent the PROPERTY entity and its purchase offer attributes using the notation for multivalued attributes.
2.Represent the PROPERTY entity and its purchase offer attributes using two entity types.
3.Assume the agency decides to also keep data about buy-ers and potential buyers, including their name, phone number, and address. Buyers often have multiple phone numbers and addresses, which are not necessarily related to each other. Augment your answer to Problem and Exercise 8.62b (located at the end of chapter 8) to accommodate this new entity type.
4.Finally, assume that, for each purchase offer, we need to know which buyer phone number and address to associate with that offer. Augment your answer to Problem and Exercise 8.62c to accommodate this new requirement.

Answer 1

In a real estate database, the PROPERTY entity and its purchase offer attributes can be represented using multivalued attributes or two entity types.

The database can also include an entity type for buyers with multiple phone numbers and addresses. Specific buyer phone numbers and addresses can be associated with each purchase offer.

Step-by-step explanation:

1. Representing the PROPERTY entity and its purchase offer attributes using the notation for multivalued attributes can be done by showing the multivalued attribute within double oval brackets. For example: PROPERTY [[$purchaseOffer]]

2. Representing the PROPERTY entity and its purchase offer attributes using two entity types can be done by creating a separate entity type for the purchase offer. For example: PROPERTY <-- PURCHASE OFFER

3. To accommodate the new entity type for buyers and potential buyers, we can add another entity type called BUYER with attributes like name, phone number, and address. Multiple phone numbers and addresses can be represented as multivalued attributes. For example: PROPERTY <-- PURCHASE OFFER --> BUYER [[$phoneNumbers]], [[$addresses]]

4. To associate a specific buyer phone number and address with each purchase offer, we can add attributes to the PURCHASE OFFER entity type. For example: PURCHASE OFFER [buyerPhoneNumber], [buyerAddress]