有学生表和成绩表，查询男女生平均成绩各是多少 。

[petrie]

这样写对吗

select Ssex，avg(grade)
                    from sc,student
group by Ssex; 

[huangdh12]

回答是 这样写是正确的

[petrie]

我该相信WHO

[ssqtjffcu]

select sex,avg(grade) from student,sc where student.sno=sc.sno group by sex

[luoyoumou]

-- 两表链接条件呢？

[ngx20080110]

select 性别,avg(grade)
from 表
group by 性别;

[petrie]

[Quote=引用楼主 lpfvip2008 的回复:]
这样写对吗SQL code
select Ssex，avg(grade)
from sc,student
group by Ssex;
[/Quote]
能帮忙写一个不？

[tangren]

--根据学生编号(sno)关联
select Ssex，avg(grade)
                    from sc,student where sc.sno=student.sno
group by Ssex;

[petrie]

[Quote=引用 4 楼 tangren 的回复:]

SQL code
--根据学生编号(sno)关联
select Ssex，avg(grade)
from sc,student where sc.sno=student.sno
group by Ssex;
[/Quote]
聚集函数能嵌套吗？

[hello_Amy]

你学生表和成绩表之间肯定要有关联啊，

[心中的彩虹]

[Quote=引用楼主 lpfvip2008 的回复:]
这样写对吗

SQL code
select Ssex，avg(grade)
from sc,student
group by Ssex;
[/Quote]


select Ssex，avg(grade)
from sc,student
where sc.no=student.no --学号关联吧
group by Ssex;

[developer2002]

基础实在太差！