Chapter 7 Excercises

Chapter 7 Excercises - columns In addition 3NF doesn’t...

This preview shows page 1. Sign up to view the full content.

Chapter 7 Problem 13 Insertion anomalies: - Inserting a new category number requires inserting an expense report number. - Inserting a new expense report number forces to insert a new category number. Update anomalies: - If I update the category name or limit, I have to update it in every row with that category number. - If I change the expense report date, I need to change it in every row with that expense report id. Delete Anomalies: - Deleting an expense report may cause the category to be deleted. Chapter 7 Problem 14 2NF doesn’t allow any FDs in which part of the key determines a nonkey. In our example, all FDs except one have only 1 column on the LHS. The FD that has two columns is ERNo, CatNo -> ExpItemNo. But both columns on the LHS determine the ExpItemNo. Hence, the given FDs don’t violate 2NF. Chapter 7 Problem 15 3NF doesn’t allow any FDs in which the nonley column determines other nonkey
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: columns. In addition, 3NF doesn’t allow any transitive dependencies. In the FD UserNo-> UserFirstName, UserLastName, UserPhone, UserEmail, the nonkey column UserEmail determines the user’s first and last name and the phone number. In the FD ExpItemNo->ExpItemDesc, ExpItemDate, ExpItemAmt, CatNo, ERNo, the nonkey columns CatNo and Erno determine the ExpItemDesc, ExpItemDate, ExpItemAmt. There is a transitive dependency. CatName determines CatNo. CatNo determines CatLimit. Hence CatName determines CatLimit. But CatName is a nonkey column. Corrected FDs: ErNo -> UserNo, ERSubmitDate ExpItemNo -> ExpItemDesc, ExpItemDate, ExpItemAmt UserNo-> UserFirstName, UserLastName, UserPhone CatNo->CatLimit ERNo, CatNo -> ExpItemNo UserEmail->UserNo CatName->CatNo...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online