Use an example of the Employee entity type to justify how a unary 1: N relations

Question

Use an example of the Employee entity type to justify how a unary 1: N relationship works. Assume that, at PVF, produces are composed of components, products are assigned to salespersons, and components are produced by vendors. Also assume that, in the relation PRODUCT (Prodname, Salesperson, Compname, Vendor), Vendor is functionally dependent on Compname and Compname is functionally dependent on Prodname. Eliminate the transitive dependency in the relation and form 3NF relations. Transform the E-R diagram of Figure 8-23 into a set of 3NF relations. Make up a primary key where needed and one or more nonkey attributes for each entity. Consider the E-R diagram of Figure 9-21. a. Transforms this E-R diagram into a set of 3NF relations. b. State and justify all reference integrity rules for the 3NF relations you created in Problem and Exercise 9-45a.

Explanation / Answer

9.45 a 3NF relations

VENDOR(Vendor_ID,Address)

PRICE_QUOTE(Vendor_ID,Item_Number,Quote_Quantity,Price)

PART(Item_Number,Description)

PART_RECEIPT(Order_Number,Date,Order_Quantity,Quote_Quantity)

underlined are primary keys and italicised are foreign keys. Some attributes are both

b

Referential integrity rules

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