select *
from Student
where Sex='男' and 
	year(Birth)-(select year(Birth)from Student--这里是需要告诉查询的表名,相当于嵌套
	where Sname='林红')

select sc.sno,sname, course.Cno,Cname,Grade,Sex
--这里如果两个表中都有同一个属性,则需要标明在哪个表,如sc.sno
from student,sc,Course
where student.Sno=sc.Sno and Sc.Cno=course.Cno

select sc.sno ,sname , Cname , Grade
from student s , course c, sc
where s.sno=sc.sno and c.cno=sc.cno

select sc.Sno,sname from student inner join sc on
student.Sno=sc.Sno inner join course on sc.Cno =course.cno
and Cname='C语言程序设计'

select sc.Sno,sname from student,sc,course where
student .Sno=sc.Sno and sc.Cno =course.cno
and Cname='C语言程序设计'

select Sno,sname from student where Sno in
(select Sno from sc where Cno=
(select cno from course where Cname ='C语言程序设计'))

select a.Sno,a.sname,a.Home_addr from student a,student b 
where a.Classno =b.Classno and b.Sname ='张虹' and a.Sname!='张虹'

select Sno,sname,Home_addr  from student where
classno=(select classno from student where sname='张虹')
and sname!='张虹'

select Sno,sname,Home_addr  from student where
classno!='051' and Birth

select Sno,sname,Home_addr  from student where
classno!='051' and Birth

select Sname from student
where not exists (
select * from course
where not exists (
select * from sc
where sno=student. sno
and cno=Course.cno))

select Sno, Sname from student
where sno in (
select distinct sno from sc as sc1
where not exists (
select * from sc as sc2 where sc2.sno='20110002'
and not exists (
select * from sc as sc3 where sc3.Sno=sc1.sno and
sc3.cno=sC2.cno) )
)

select sc.Sno, sc.cno , grade from sc where
grade >all(select grade from sc where cno='002' ) and
Cno= (select Cno
from course where Cname='高数')
order by Grade desc

select sno,SUM(grade) from sc where sno in (select Sno from sc group by sno
having COUNT(*)>=3) and Grade>=60 group by sno
order by SUM (grade) desc

select avg(Grade) as 平均成绩
from sc
where Cno like '%3' group by cno
having count (Cno)>3

select distinct sc.sno 学号,sname 姓名,
max (grade) as最高分,min (grade) as最低分
from student,sc
where sc.sno=student.Sno group by sc.sno , Sname
having max(grade) -min (grade) >5

create table student__other (
Sno char (8) primary key,
Sname varchar (8) not null,
sex char(2) not null,
Birth smalldatetime not null,
Classno char (3) not null,
Entrance_date smalldatetime not null,
Home_addr varchar (40) ,
sdept char (2) not null,
Postcode char (6)
)

select * from student__other so ,student s
where so.sno=s.sno

select * from student
union
select * from student__other