WorksheetsDBMS Quiz-1 (BCS3C)
Total questions: 10
Worksheet time: 15mins
Which of the following FD is redundant. For R(A,B,C), the set of FDs F(A-> AB, B-> C, A->B, C->B, B->A).
A->AB
B->C
B->A
None of the above
What are the prime attributes for the R = {A,B,C,D,E} with set of Fds Z={D -> E , CE-> A}
BCD
AE
CDE
CE
Given the following relation instance.
Which of the following functional dependencies are satisfied by the instance?
XY -> Z and Z -> Y
YZ -> X and Y -> Z
YZ -> X and X -> Z
XZ -> Y and Y -> X
Consider a relation scheme R = (A, B, C, D, E, H) on which the following functional dependencies hold: {A–>B, BC–>D, E–>C, D–>A}. Identify the candidate keys of R.
(a)
In a schema with attributes A, B, C, D and E, following set of functional dependencies are given:
A->B
A->C
CD->E
B->D
E->A
Identify the functional dependencies which is NOT implied by the above set.
CD->AC
BD->CD
BC->CD
AC->BC
Consider the given table Loan_Records. Select the output of the following SQL query.
3
9
5
6
The relation book (title, price) contains the titles and prices of different books. Assuming that no two books have the same price, what does the following SQL query list?
Titles of the four most expensive books
Title of the fifth most inexpensive book
Title of the fifth most expensive book
Titles of the five most expensive books
How can you change "Dibyarup" into "Sayan" in the "LastName" column in the Users table?
UPDATE User SET LastName = 'Dibyarup' INTO LastName = 'Sayan'
MODIFY Users SET LastName = 'Sayan' WHERE LastName = 'Dibyarup'
MODIFY Users SET LastName = 'Dibyarup' INTO LastName = 'Sayan'
UPDATE Users SET LastName = 'Sayan' WHERE LastName = 'Dibyarup'
Suppose the following functional dependencies hold on a relation U with attributes P, Q,R, S, and T:
P → QR
RS → T
Which of the following functional dependencies can be inferred from the above functional dependencies?
P → R
PS → T
R → T
PS → Q
Consider the relations R(A, B) and S(B, C) and the following four relational algebra queries over R and S:
Where R.B refers to the column B in table R. One can determine that:
i, ii and iii are the same query
i, iii and iv are the same query
ii, iii and iv are the same query
i, ii and iv are the same query
