--不分学科
select *,
rank()over(order by 成绩 desc) as 名次 from tbl
--分学科
select *,
rank()over(partition by 课程 order by 成绩 desc) as 名次 from tbl

------解决方案--------------------
SQL code
select *,名次=(select count(*) from tb where 成绩>=a.成绩)
from tb a order by 成绩 desc

------解决方案--------------------
SQL code

SELECT *，名次=ROW_NUMBER() OVER (ORDER BY 成绩 DESC) FROM tb ORDER BY 成绩 DESC