sql="select users.*,sum(IFNULL(0,student_works.final_score))/#{homework_count} score from student_works left outer join users on student_works.user_id = users.id"<<
" where homework_common_id in ( select id from homework_commons where homework_commons.course_id = #{course.id}) GROUP BY student_works.user_id ORDER BY score limit 0,5"
sql="select users.*,sum(IFNULL(0,student_works.final_score))/#{homework_count} score from student_works left outer join users on student_works.user_id = users.id"<<
" where homework_common_id in ( select id from homework_commons where homework_commons.course_id = #{params[:course_id]}) GROUP BY student_works.user_id ORDER BY score limit #{page*10},10"