MySQL Query Ranking

I have this MySQL query for list a "Vote Ranking" for "Actions" and it work fine, but I want what the "id_user" doesn't repeat, like made a "DISTINCT" in this field.

SELECT
count(v.id) votos, 
v.id_action,
a.id_user,
a.id_user_to,
a.action,
a.descripcion
FROM
    votes v,
    actions a
WHERE
    v.id_action = a.id
GROUP BY
    v.id_action
ORDER BY
    votos DESC

The result:

votes  act     开发者_如何学Cid_user
3      3       745059251
2      20      1245069513
2      23      1245069513
2      26      100000882722297
2      29      1245069513
2      44      1040560484
2      49      1257441644
2      50      1040560484

The expected result

votes  act  id_user
3      3    745059251
2      20   1245069513
2      26   100000882722297
2      44   1040560484
2      49   1257441644
2      50   1040560484

If you don't want duplicate users, you should group by a.id_user only. Then you will have to aggregate your actions, so you may want a sum(a.action) or count(a.action) in place of a.action. It's hard to tell what you should use without knowing what an 'action' represents.