update table using condition
You have to join tables like that: (not an actual query)

UPDATE City AS w
  JOIN Cars AS z ON z.id = w.car_id -- some real condition needed
   SET w.status='good'
 WHERE z.car_id=123 
   AND w.city_id IS NULL 
   AND w.country IS NULL
   AND w.person_id=789
;


Show your tables for more specific code.