select user_group,user_score/user_num avg_score from
(
SELECT user_group,SUM(Users.user_score) AS user_score, SUM(Users.user_) AS user_num
FROM Users
group by user_group
) t
order by avg_score
(
SELECT user_group,SUM(Users.user_score) AS user_score, SUM(Users.user_) AS user_num
FROM Users
group by user_group
) t
order by avg_score
SELECT SUM(Users.user_score) AS user_score, SUM(Users.user_) AS user_num
FROM Users
group by user_group ) x
ORDER BY user_score/user_num
FROM Users
group by user_group
order by avg_score