SELECT rt.tag,rt.difficulty, ROUND((sum(score) -max(score) -min(score))/ (count(score)-2),1) as clip_avg_score from exam_record er join examination_info rt USING(exam_id) where rt.tag='SQL' and rt.difficulty='hard';
SELECT rt.tag,rt.difficulty, ROUND((sum(score) -max(score) -min(score))/ (count(score)-2),1) as clip_avg_score from exam_record er join examination_info rt USING(exam_id) where rt.tag='SQL' and rt.difficulty='hard';