sql ex ru excercise data mismatch question 63

Question

there are two tables

Passenger(ID_psg, name)
Pass_in_trip(trip_no, date, ID_psg, place)

on which you should find the names of passangers who has travelled more than once on the exact same seat more precisely the question is like this:

Find the names of different passengers that ever travelled more than once occupying seats with the same number

both tabels are linked to eachother thropugh the id_psg the column which contains the seat is place from pass_in_trip which contains which passenger name was seated there via id_psg

my current code is:

with a(name, heret) as (
select pr.name , count(p.place) as heret from passenger pr 
join pass_in_trip p on
pr.id_psg = p.id_psg
group by pr.name , p.place
)

select distinct name from a 
where heret > 1

on which i grouped the passengers names with their place(seat), i got the correct result in the first database but it had data mismatch on the second one, can anyone help me to understand what is wrong in this situation?

Answer 1

Name isn't an integer, it is likely a string of some type. You will need to use a COUNT() with a group by quite likely.

Answer 2

looks like the problem was on the join operation this is the correct code for anyone who faces similar obstacle

select name from Passenger where id_Psg IN (
select p.ID_psg from
pass_in_trip p 
group by p.ID_psg, p.place
having count(p.place) > 1 )

search for the names whose id_psg results in that subquerie