Question

Consider a relation train with attributes trainid (Primary Key), trainname, traintype, noofcoaches, source and destination. Except trainid, no columns am The table has following 3 indexes created:

IX1-trainname, source

IX2- trainname, destination

IX3 noofcoaches

Which of the following will NOT use index?

Answer 1

SELECT pid
FROM Reservation ,
WHERE class ‘AC’ AND
    EXISTS (SELECT *
       FROM Passenger
       WHERE age > 65 AND
       Passenger. pid = Reservation.pid)