可能是我写错题目了.是输出系名.
就是看哪个系的平均年龄是否大于20.

非常感谢你的支持和帮助.
以后请你多教教我啊.
大家多帮帮我啊.谢谢各位.

视图的语法不是这样的。
假设有这一个表
create table student
(
sno varchar(3)
primary key,
thename varchar(8),
age int,
dpet varchar(2)
)
go
要创建一个只看thename和dpet的视图的语法为
create view v1
as
select thename,dpet from strudent
go

是我写错了,丢了点,应该是
creat view view4(sdept,avgsage)
as
select sdept,avg(sage)
from s
group by sdept
having avg(sage)>20

我把源码都给你吧
下面是建立表的。
create table student
(
sno varchar(3)
primary key,
thename varchar(8),
sex bit default 0, --0为男，1为女
age int check (age>0),
zy varchar(10) --专业
)
go

create table class
(
cno varchar(3)
primary key,
classname varchar(10)
)
go

create table checkclass
(
sno varchar(3) not null,
cno varchar(3) not null,
primary key(sno,cno),
grade int check(grade>0)
)
go
下面是试验的数据。
insert into class values ('001','English')
insert into class values ('002','Chinese')
insert into class values ('003','Computer')
insert into class values ('004','Math')
insert into student values ('001','王一',0,23,'计算机')
insert into student values ('002','赵二',1,21,'外语')
insert into student values ('003','张三',0,24,'数学')
insert into student values ('004','李四',0,22,'计算机')
insert into student values ('005','刘五',0,26,'物理')
insert into student values ('006','孙六',1,20,'计算机')
insert into checkclass (sno,cno)
select sno,cno from student,class
where sno<>'004' and cno <>'001'
insert into checkclass (sno,cno)
select sno,cno from student,class
where sno='004'
declare ingrade cursor
for select * from checkclass
open ingrade
fetch next from ingrade
while @@FETCH_STATUS = 0
begin
update checkclass set grade=rand()*100
where current of ingrade
fetch next from ingrade
end
下面是我自己做的前三题的答案，如果有不对的地方别笑我呀。

create view noenglish
as
select thename from student where sno not in (select sno from checkclass,class
where checkclass.cno=class.cno and classname='english')
go

create view allcheck
as
select thename from student
where exists
(select sno ,count(cno) from checkclass
group by sno
having count(cno)=(select count(*) from class) and student.sno=checkclass.sno )
go

create view three
as
select cno,avg(grade) from checkclass
group by cno
having avg(grade)>50
go

第四题我觉得应该做不出来，姓名是多行的，平均年龄是单行的，怎么可能放在一张表中。

谢谢帮忙.