SQL Gateforum

Question

A relation schema  for a bus reservation is given below.

Bus(BusNo, Bname, travel-agent)
Passenger (Pid,pname,age)
Reservation (Pid,class,travel-Agent)

Comments

None of these

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how EXIST react to empty set?

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Exist on empty retuen false i.e. does not select that record.

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there is also syntax error in last line Pid=(select Pid from passengers where age=30), in place of '=' there should be 'IN'