91Ó°ÊÓ

What is meant by the attribute preservation condition on a decomposition?

Discuss the null value and dangling tuple problems.

What is a multivalued dependency? What type of constraint does it specify? When does it arise?

Define fourth normal form. When is it violated? Why is it useful?

Define join dependencies and fifth normal form. Why is \(5 \mathrm{NF}\) also called project. join normal form (PJNF)?

What types of constraints are inclusion dependencies meant to represent?

Why is the domain-key normal form (DKNF) known as the ultimate normal form?

, YEAR, PRICE, MANUF_PLANT, COLOR), which is abbreviated as REFRIG(M, Y, P, MP, C), and the following set \(F\) of functional dependenci… # Consider the relation REFRIC(MODEL#, YEAR, PRICE, MANUF_PLANT, COLOR), which is abbreviated as REFRIG(M, Y, P, MP, C), and the following set \(F\) of functional dependencies: \(F=\\{M \rightarrow M P,\\{M, Y\\} \rightarrow P, M P \rightarrow C\\}\) a. Evaluate each of the following as a candidate key for REFRIG, giving reasons why it can or cannot be a key: \(\\{\mathrm{M}\\},\\{\mathrm{M}, \mathrm{Y}\\},\\{\mathrm{M}, \mathrm{C}\\}\) b. Based on the above key determination, state whether the relation REFRIG is in \(3 \mathrm{NF}\) and in BCNF, giving proper reasons. c. Consider the decomposition of REFRIG into \(D=\\{\mathrm{R} 1(\mathrm{M}, \mathrm{Y}, \mathrm{P}), \mathrm{R} 2(\mathrm{M}, \mathrm{MP}, \mathrm{C})\\}\) Is this decomposition lossless? Show why. (You may consult the test under Property LJ 1 in Section \(11.1 .4 .\)