Show me id and descriptions of all the skills.
select skill_id, skill_description from skills
For each of those skills, show the number of faults each skill is used to fix.
select t1.skill_id, t1.skill_description, count(*) from skills as t1 join skills_required_to_fix as t2 on t1.skill_id = t2.skill_id group by t1.skill_id order by count(*) desc limit 1
Which skill is used to fix the most number of faults?
select t1.skill_id, t1.skill_description from skills as t1 join skills_required_to_fix as t2 on t1.skill_id = t2.skill_id group by t1.skill_id order by count(*) desc limit 1