Which parts have less than 2 faults? Show the id and name of that part.
select t1.part_name, t1.part_id from parts as t1 join part_faults as t2 on t1.part_id = t2.part_id group by t1.part_id having count(*) < 2
Do the same for parts with more than 2 faults.
select t1.part_name, t1.part_id from parts as t1 join part_faults as t2 on t1.part_id = t2.part_id group by t1.part_id having count(*) > 2