第四章：高级查询

--上机1  
select MAX(studentresult) as '最高分',MIN(studentresult) as '最低分' from result where  
subjectid=(select subjectid from subject where subjectname='oop')  
and examdate=(select MAX(examdate) from result   
where subjectid=(select subjectid from subject where subjectname='oop'))  
  
--上机2  
select subjectname from subject where subjectid in   
(select subjectid from subject where gradeid=(select gradeid from grade where gradename='S1'))  
  
--上机3  
select studentname from student where studentno not in(  
select studentno from result where subjectid=(select subjectid from subject where subjectname='SQL')   
and examdate=(select MAX(examdate) from result where subjectid=(  
select subjectid from subject where subjectname='java'))) and gradeid=1  
  
--上机4  
if exists(select studentno from student where gradeid=(select gradeid from grade where gradename='S1'))  
begin  
update student set gradeid=(select gradeid from grade where gradename='S2') where gradeid=(select gradeid from grade where gradename='S1')  
end