How to do an INNER JOIN on multiple columns

Question

I\'m working on a homework project and I\'m supposed to perform a database query which finds flights either by the city name or the airport code, but the flights

Answer 1

if mysql is okay for you:

SELECT flights.*, 
       fromairports.city as fromCity, 
       toairports.city as toCity
FROM flights
LEFT JOIN (airports as fromairports, airports as toairports)
ON (fromairports.code=flights.fairport AND toairports.code=flights.tairport )
WHERE flights.fairport = '?' OR fromairports.city = '?'

edit: added example to filter the output for code or city