COMP 353_Midterm winter 2024 practice exam solution Concordia University

COMP 353_Midterm winter 2024 practice exam solution Concordia University




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Question 1
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Question text
Let R(A,B,C,D, E) be a relation with FDs F = {AB→CD, A→E, C→D, D→E}
The decomposition of R into R1(A, B, C), R2(B, C, D) and R3(C, D, E) is (2 Points)


Select one:
Lossy and Dependency Preserving.
Lossless and Not Dependency Preserving.


Lossless and Dependency Preserving.
Lossy and Not Dependency Preserving.

Question 2
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, Question text
Suppose R is a one-to-one relationship from R1 = { a, b, c, d} to R2 = {e, f, g, h}.
Of the following sets, which one is NOT a valid instance of R? (2 Points)
Select one:

{}, the empty set.
{(c, g)}.
{(a, e),(b,f),(b,g)}.



{(a, h), (b, g), (c, f), (d, e)}.
All of the above.
None of the above.

Question 3
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Question text
Let R(A,B,C,D,E) be a relation with FDs F = {ABC→D, BD→A, E→B} (2 Points)
Select one:

R has more than three candidate keys.


R has exactly three candidate keys.


R has exactly one candidate key.
R has exactly two candidate keys.



Question 4
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