下面是我学习sql语句中的出错的和疑问，算是总结。
8. exclusive or (xor). show the countries that are big by area or big by population but not both. show name, population and area.
australia has a big area but a small population, it should be included.indonesia has a big population but a small area, it should be included.china has a big population and big area, it should be excluded.united kingdom has a small population and a small area, it should be excluded.
select name,population,area from world where ((area < 3000000 and population>250000000) or (area > 3000000 and population < 250000000))
有没有更简单的写法？