4430 A2 #3

SELECT * from (enrolled left join class
on enrolled.cname=class.cname)
union
SELECT * from (enrolled right join class
on enrolled.cname=class.cname);

SELECT *from (class left join faculty
on class.fid=faculty.fid)
union
SELECT * from (class right join faculty 
on class.fid=faculty.fid);

select student.sname, group_concat(class.cname), count(faculty.fid) as count
from student
inner join enrolled on student.snum = enrolled.snum
inner join class on class.cname = enrolled.cname
inner join faculty on faculty.fid = class.fid

group by student.sname, faculty.fid
having count(faculty.fid) = 2

This is crazy:
SELECT *
FROM (((student
left join enrolled
on student.snum=enrolled.snum)
left join class
on enrolled.cname=class.cname)
left join faculty
on class.fid=faculty.fid)
union
select *
FROM (((student
right join enrolled
on student.snum=enrolled.snum)
right join class
on enrolled.cname=class.cname)
right join faculty
on class.fid=faculty.fid);