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

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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
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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...
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