{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}


HomeworkAssignment2 - 8.Customer is fine Sale has way too...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Jerome Azarewicz IST 210 2/11/08 Homework 2 A. (Figure2-30(a)) Phone  depends on   FirstName  and  LastName Total  depends on  Item Price  and  Tax (Figure 2-30(b)) PurchasePrice  depends on  Item Phone  depends on  Vendor B. 1. Not Good. Needs another primary Key, last name is too simple and can easily be  duplicated (i.e. someone have the same last name) 2. Good. 2 primary keys that are not likely to have duplicate information. 3. Good. 2 primary keys that are not likely to have duplicate information. 4. Unnecessary Information. PurchaseDate should not be part of the primary key since both  FirstName and LastName are already primary keys and are of sufficient value. 5. Not Good. Too many primary keys, unnecessary. 6.Customer is fine, Sale is not fine. PurchaseDate should not be primary key; Item should  be. 7. Both Customer and Sale are fine. They both compliment eachother.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Background image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 8.Customer is fine. Sale has way too many items. LastName and FirstName are completely unnecessary. C. CustomerID(LastName, FirstName , Phone, Email, SalesID ) Sales(SalesID , Item, Price, Tax, Total, PurchaseDate) It is better because it is much more specific and the information is stored in a area where it would be accessed easily. Also, the surrogate is short and simple and will never change. D. Sale( Total , Date, Item ) SaleItem(Item , Price, Vendor) It improves it by causing less information to be in one place and being able to reference it in different tables. You are able to find out the necessary information in SALE, and if necessary, you can look up the information for the item being sold....
View Full Document

{[ snackBarMessage ]}