SQL排序

今天经理出了题SQL语句：每个学生按照语文成绩的排名，如果没有成绩那就排名最后，要求有列 排名名次，学生姓名，成绩
2张表分别：

 rank () over：

select rank () over (order by a.Score desc ) as 排名名次,a.SName as 学生姓名,a.Score as 成绩 from
(select TScore.Score as score,TStudent.SName from TStudent left join TScore on TScore.Sno =TStudent.SNo
where isnull(TScore.CourseID,'A02')='A02') as a order by a.Score desc 

如果成绩为空的话序号就都显示一样

row_number() over ：

select row_number() over  (order by a.Score desc ) as 排名名次,a.SName as 学生姓名,a.Score as 成绩 from
(select TScore.Score as score,TStudent.SName from TStudent left join TScore on TScore.Sno =TStudent.SNo
where isnull(TScore.CourseID,'A02')='A02') as a order by a.Score desc 

row_number() over 按照行来排序

dense_rank () over：

select dense_rank () over(order by a.Score desc ) as 排名名次,a.SName as 学生姓名,a.Score as 成绩 from
(select TScore.Score as score,TStudent.SName from TStudent left join TScore on TScore.Sno =TStudent.SNo
where isnull(TScore.CourseID,'A02')='A02') as a order by a.Score desc 

如果成绩是一样的话，序号也显示一样，好比说John的成绩是77，那他的排名也是3，而Marry的排名是4