SQL不明白 - MS-SQL Server / 应用实例

查询学生平均成绩及其名次 
  SELECT 1+(SELECT COUNT( distinct 平均成绩) 
  from (SELECT S#,AVG(score) AS 平均成绩 
  from SC 
  GROUP BY S# 
  ) AS T1 
  WHERE 平均成绩 > T2.平均成绩) as 名次, 
  S# as 学生学号,平均成绩 
  from (SELECT S#,AVG(score) 平均成绩 
  from SC 
  GROUP BY S# 
  ) AS T2 
  ORDER BY 平均成绩 desc; 
语句不是很理解啊。帮下我吧

---

语言不太好表达，帮顶吧

---

SQL code:

--计算均分
SELECT S#,AVG(score) 平均成绩
from SC
GROUP BY S#

--按照学号计算平均分，并取得高于均分的同学的个数
SELECT COUNT( distinct 平均成绩)
from (SELECT S#,AVG(score) AS 平均成绩
from SC
GROUP BY S#
) AS T1
WHERE 平均成绩 > T2.平均成绩

--不过不知道为何+1？

---

SQL code:

--哦，这样一目了然了，其实你就是在给学生排名次。
create view view_acg_scor as select s# 学号,avg(score) 平均成绩 from SC group by s#
SELECT 1+(SELECT COUNT( distinct 平均成绩)
from view_acg_score AS T1