Count movies with specific score, per actor
You can group by actor_id to get the desired results. You might want to join groups in as well if you want to filter by a column in there. (sqlfiddle)

SELECT
    actor_id,
    COUNT(CASE WHEN score &gt;= 0 and score &lt;= 1 THEN 1 END) count0,
    COUNT(CASE WHEN score &gt; 1 and score  &lt;= 2 THEN 1 END) count1,
    COUNT(CASE WHEN score &gt; 2 and score  &lt;= 3 THEN 1 END) count2,
    COUNT(CASE WHEN score &gt; 3 and score  &lt;= 4 THEN 1 END) count3,
    COUNT(CASE WHEN score &gt; 4 and score  &lt;= 5 THEN 1 END) count4,
    COUNT(CASE WHEN score &gt; 5 and score  &lt;= 6 THEN 1 END) count5,
    COUNT(CASE WHEN score &gt; 6 and score  &lt;= 7 THEN 1 END) count6,
    COUNT(CASE WHEN score &gt; 7 and score  &lt;= 8 THEN 1 END) count7,
    COUNT(CASE WHEN score &gt; 8 and score  &lt;= 9 THEN 1 END) count8,
    COUNT(CASE WHEN score &gt; 9 and score  &lt;= 10 THEN 1 END) count9
FROM movies
 INNER JOIN movies_actors ON movies_actors.movie_id = movies.id 
 INNER JOIN actors ON movies_actors.actor_id = actors.id
WHERE actors.group_id = 1
GROUP BY actor_id