select (select count(*) from class b where b.Nnumber>=a.Nnumber) as 名次,
name as 姓名,Nnumber as 成绩 from class a ORDER BY Nnumber DESC
name as 姓名,Nnumber as 成绩 from class a ORDER BY Nnumber DESC
name as 姓名,Nnumber as 成绩 from class a ORDER BY Nnumber DESC