rank(),允许并列名次、复制名次自动空缺,结果如12245558……
将score按ID分组排名:rank() over(partition by id order by score desc)
将score不分组排名:rank() over(order by score desc)
select id,area,score,
rank() over(partition by id order by score desc) 分组id排序,
rank() over(order by score desc) 不分组排序
from students order by id,area;