43. Table Q{A , B , C , D} and a set of functional dependencies
A → B, C
D → C
The closure of {A D } is:
a) A D
b) A D B C
c) B C
d) None of the above
44. Consider the relation student(sno, sname, cname, cno) where
(sno, cno) or (sname,
cname) are candidate keys. There are functional dependencies
within the keys.
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The highest normal form whose requirements this relation
satisfies is:
(a) 1NF
(b) 2NF
(c) 3NF
(d) BCNF
45. Let R be a relation with attributes (B,I,N,R,U,L) and let the
following functional
dependencies hold.
B → I
B → N
N R → U
N R → L
I → U
Given the above functional dependencies, which of the following
functional dependencies does
not hold:
a) N R → U L
b) B R → L
c) B → U
d) I→ N R
46. Suppose relation R(S,G,F,Y,N) has the following functional
dependencies:
S → G
G → F
G F → S
S → Y
N → S
Y → N
Which of the following is not a key?
a) N b) G,F
c) S d) Y
47. Table TT {A , N , H , K , J , O , X } and a set of functional
dependencies
A, N → O, X
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J → A , N, H
H, O → K, X
H, K, X → O
A, N, X → J
The closure of {A N } is:
e) A H K X J O
f) A N H K X J
g) A N H X J O
h) A N H K X J O
48. Consider the follow attributes and functional dependencies:
A B C D E F H
A→ D
AE → H
DF → BC
E → C
H → E
List all keys (not superkeys):
49. (Đề 48) Consider the decomposition into 3 relations: (AD) (EC)
(ABEFH). Is this
decomposition in
(a) BCNF
(b) 3NF
(c) 1NF
(d) None of the above
