gistfile1.rb

    sql = 'SELECT ctr.id, ctr.code as country_code, ctr.name as country_name, c.id, c.country_id, 
      c.code as city_code, c.name as city_name, a.code as airport_code, a.name as airport_name, a.city_id
      FROM countries AS ctr INNER JOIN cities AS c INNER JOIN  airports AS a 
      ON (ctr.name = ? OR ctr.code = ? OR c.name = ? OR c.code = ? OR a.code = ? OR a.name = ?) 
      AND ctr.id = c.country_id AND a.city_id = c.id'
    sql = ActiveRecord::Base.send(:sanitize_sql_array, [sql, name.upcase, name, name.upcase, name, name.upcase, name])
    result_hash = ActiveRecord::Base.connection.execute(sql)
    
    ## Result (development)
    SELECT ctr.id, ctr.code as country_code, ctr.name as country_name, c.id, c.country_id, 
     c.code as city_code, c.name as city_name, a.code as airport_code, a.name as airport_name, a.city_id
     FROM countries AS ctr INNER JOIN cities AS c INNER JOIN airports AS a 
     ON (ctr.name = 'Москва' OR ctr.code = 'Москва' OR c.name = 'Москва' OR c.code = 'Москва' OR a.code = 'Москва' 
     OR a.name = 'Москва') AND ctr.id = c.country_id AND a.city_id = c.id