--------上機練習1------
select max(StudentResult),min(StudentResult) from result
where examdate=
(
   select max(examdate) 
   from result where subjectid=
          (
             select subjectid 
             from subject where subjectname='oop'
          )
)
and subjectid=
(
    select subjectid 
    from subject where subjectname='oop'
)
 
----上機練習2------
select subjectname from subject
where gradeid in (select gradeid from grade where gradename='S1')
----上機3----
select studentname,studentno from student
where studentno not in(
  select studentno 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')
	)
)and gradeid=(select gradeid from grade where gradename='S1')
-----上機4-----
if exists (
select * from  student 
where gradeid=(select gradeid from grade where gradename='S1')
)
begin 
update student set gradeid='2'
where gradeid='1'
end