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Introduction

Normal From是數(shù)據(jù)庫(kù)理論里面最?lèi)盒牡膯?wèn)題，從1NF到6NF，加上BCNF，DKNF以及UF。不像編程作業(yè)，有運(yùn)行結(jié)果作參考，做這種理論題簡(jiǎn)直是受罪，每一題都得反復(fù)推理。
像下面給出的這個(gè)作業(yè)，除了題量大以外，每個(gè)問(wèn)題都是多解問(wèn)題，拿滿分幾乎是不可能的事情。

Requirement

1) For this problem you will consider following relation and set of FDs:

R(A,B,C,D,E)
AB → E
B → C
CE → A
AE → D
a) What are the keys of R?
b) Show that the set of FDs is a minimal basis; if it is not a minimal basis, find a minimal basis for the FDs.
c) What are all of the BCNF violations that follow from the FDs? (Don’t just consider the listed FDs, but all that follow).
d) Decompose R into BCNF. For each relation, list the keys, and make sure the set of FDs for each is a minimal basis.
e) What are all of the 3NF violations that follow from the FDs? (Don’t just consider the listed FDs, but all that follow).
f) Decompose R into 3NF. For each relation, list the keys, and make sure the set of FDs for each is a minimal basis.
g) What are all of the 4NF MVD violations that follow from the FDs?
h) Decompose R into 4NF. For each relation, list the keys, FDs and MVD.
i) If you project the relation R onto S(A,B,C) what nontrivial FDs and MVDs hold in S?

2) For this problem you will consider the following relations and FDs:

Courses(C,T,H,R,S,G)
C → T
HR → C
HT → R
HS → R
CS → G
Where C, T, H, R, S, and G are the course, teacher, hour, room, student, and grade respectively. With a proposed decomposition of:
R1(C, T, H)
R2(C, H, R, G)
R3(C, R, S)
a) Use the chase test to prove/disprove that holds HS → G in Courses.
b) Use the chase test to prove/disprove that holds THR → S in Courses.
c) Use the chase test to prove/disprove the proposed decomposition has a lossless join.
d) Decompose Courses into 3NF.
e) Which of your relations in 3NF are not in BCNF?
f) Which of your relations in 3NF are not in 4NF?

3) Design an academic genealogy database with one entity set: Academics.

Consider academics with doctoral degrees only. The information to record about academics includes their name, discipline, year of graduation, institution, dissertation title, dissertation chair, dissertation committee members (assume two others distinct from chair), and academic progeny.

Summary

最后還是想說(shuō)一下，這樣的多個(gè)解的作業(yè)真的相當(dāng)惡心，做的時(shí)候需要反復(fù)推導(dǎo)，查閱各種資料來(lái)證明，而且第二個(gè)問(wèn)的chase test完全就是slides里面的方法，學(xué)習(xí)理解也花了不少時(shí)間。