query:
SELECT sportname_nl, event_nl FROM data_schedule INNER JOIN koppel_atleet_event ON data_schedule.event_id = koppel_atleet_event.eventid WHERE medals = 1 AND atleetid = ORDER BY event_nl

has failed! You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ORDER BY event_nl' at line 1