sql script
select g.id, g.job, g.score from (select job, avg(score) as avg_score from grade group by job) tmp, grade g where tmp.job=g.job and g.score > tmp.avg_score
select g.id, g.job, g.score from (select job, avg(score) as avg_score from grade group by job) tmp, grade g where tmp.job=g.job and g.score > tmp.avg_score