--７．查询平均成绩为90分以上的学生学号、姓名和成绩；

CREATE VIEW V_AVG(sno,GAVG)
AS
SELECT sno,AVG(grade)
FROM SC
GROUP BY sno
HAVING AVG(grade)>90

SELECT sname,grade
FROM V_AVG,S
WHERE S.sno=V_AVG.sno;
这样做不对，但我想不到什么办法。要求用视图，大家帮忙改下，

CREATE VIEW V_AVG(ssno,GAVG)
AS
SELECT sno,AVG(grade)
FROM SC
GROUP BY sno
HAVING AVG(grade)>85

SELECT S.sno,sname,grade
FROM S,SC
WHERE S.sno=SC.sno AND S.sno in
(SELECT ssno
FROM V_AVG) ;
终于做出来了，大家可以看看。有什么改进告诉我