mysql - Summing values over multiple, non-related tables? -

i have 3 tables: users, sales , points.

each user has multiple sales , multiple points.

sales have column "value" , points have column "score", so

users = | user_id | name |  sales = | sale_id | user_id | value |  points = | point_id | user_id | score | 

now want show listing of users sums of sales , points so

user_id | sum(sales.value) | sum(points.value) 1       |   500            |    200 2       |   213            |    132 3  .  .  . 

is possible achieve in 1 query, without using subqueries?

or best, simpliest approach? i'm trying simplify as possible because have lots of information related users have show in manner.

i tried using left joins when join 2 one-to-many tables in 1 query, sum becomes messed because of repeated rows. tried grouping data think i'm lost.

the "right" approach in sql summarize tables before joining them:

select u.user_id, sumvalue, sumscore users u left outer join      (select user_id, sum(value) sumvalue       sales       group user_id      ) s      on u.user_id = s.user_id left outer join      (select user_id, sum(score) sumscore       points       group user_id      ) p      on u.user_id = p.user_id;