Which is the weakest normal form that the new database satisfies, but the old one does not?
Answer : Option AExplaination / Solution:
candidate key is (volume, number, start page, end page)
(Volume number) → year is a partial dependency. So original table is in 1NF but not in 2NF
Q7. Consider a database that has the relation schemas EMP(EmpId, EmpName, DepId). And
DEPT(DeptName, DeptId). Note that the DeptId can be permitted to be NULL in the relation
EMP. Consider the following queries on the database expressed in tuple relational calculus.
Which of the above queries are safe?
Answer : Option DExplaination / Solution:
Query which generates infinite number of tuples is called unsafe query. In the given question
all the given queries generate finite number of tuples.
Q8.In a database system, unique time stamps are assigned to each transaction using Lamport’s
logical clock . Let TS(T1) and TS(T2) be the timestamps of transactions T1 and T2 respectively. Besides, T1 holds a lock on the resource R, and T2 has requested a conflicting
lock on the same resource R. The following algorithm is used to prevent deadlocks in the
database system assuming that a killed transaction is restarted with the same timestamp.
if TS(T2) < TS(T1) then
T1 is killed
else T2 waits.
Assume any transactions that is not killed terminates eventually. Which of the following is
TRUE about the database system that uses the above algorithm to prevent deadlocks?
Answer : Option AExplaination / Solution:
Elder kills younger and youngers waits on elder. So both are not waiting for each other. Hence
no deadlock and there won’t be any starvation as well because the transaction who got killed
will be starting with same time stamp.
Q10.Suppose the predicate F(x, y, t) is used to represent the statement that person x
can fool person y at time t. which one of the statements below expresses best
the meaning of the formula ∀x ∃y ∃t (¬F (x, y, t))?
Answer : Option DExplaination / Solution: No Explaination.
Total Question/Mark :
Scored Mark :
Mark for Correct Answer : 1
Mark for Wrong Answer : -0.5
Mark for Left Answer : 0