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select studentname, teachername from(
select max(studentid) studentid, teacherid from course where teacherid in (
select max(teacherid) from course group by studentid having count(teacherid) = 1)
group by teacherid having count(studentid) = 1) t,
student, teacher
where t.studentid=student.studentid and t.teacherid=teacher.teacherid;