A relational schema for a train reservation database is given below:

Passenger ( pid, pname, age)
Reservation (pid, cass, tid)

Table: Passenger

pid	pname	age
0	'Sachin'	65
1	'Rahul'	66
2	'Sourav'	67
3	'Anil'	69

Table: Reservation

pid	class	tid
0	'AC'	8200
1	'AC'	8201
2	'SC'	8201
5	'AC'	8203
1	'SC'	8204
3	'AC'	8202

What pids are returned by the following SQL query for the above instance of the tables?

SELECT   pid
FROM   Reservation
WHERE   class 'AC' AND 
EXISTS (SELECT * 
FROM Passenger 
WHERE age > 65 
AND Passenger.pid = Reservation.pid);

The following functional dependencies hold for relations R(A, B, C) and S(B, D, E): $$$\eqalign{ & B \to A \cr & A \to C \cr} $$$

The relation R contains 200 tuples and the relation S contains 100 tuples. What is the maximum number of tuples possible in the natural join R $$\Join$$ S?

Which of the following concurrency control protocols ensure both conflict serializability and freedom from deadlock?

I. 2-phase locking
II. Time-stamp ordering

Consider the following schedule for transactions T1, T2 and T3: Which one of the schedules below is the correct serialization of the above?