--1

select * from student
where stuno in 
(select stuno from score a,result b
where a.sno=b.sno and a.sname='数学')

--2
select * from student
where sno in 
(select sno from result 
group by sno,stuno
having count(1)>5)

--3
select * from student

select student.stuno,student.stuname from student 
inner join result on student.stuno=result.stuno  
group by student.stuno,student.stuname 
having count(result.sno)=(select count(*) from score)

 1.
 select stuNo,stuName from  Student where stuNo in(select distinct stuNo from result where sNO =(select sNO from Score where sName='数学'))
  2.
   
  select stuNO,stuName from student inner join(select 学号,count( 科目编号) from result  group by 学号 having count( 科目名称)>5)a on a.学号= student.stuNO

  3.
  select stuNO,stuName from student where not exists(select 1 from Score where not exists(select 1 from Result where Result.SNo=Score.Sno and Result.Sno=Student.SNO))