总结每个用户和跟踪的最高分数

Question

这可能很容易,但对于我的生活,我似乎无法弄明白.这是我的表:

uid  |  userID  |  trackID  |  carID  |  highscoreDate  |  highscore
-----------------------------------------------------------------
 1        1            1         1           [date]         123
 2        1            1         1           [date]          44
 3        2            2         1           [date]         222
 4        2            1         1           [date]          28
 5        1            2         1           [date]          17

我想获得的SUM的最高为每个用户和轨道高分.在上面的数据中,将给出:

 user 1: 140
 user 2: 250

Answer 1

如何先使用子选择.

就像是

SELECT userID, SUM(highscore)
FROM (
    SELECT userID, trackID, MAX(highscore) highscore
    FROM MyTable
    GROUP BY userID, trackID
  ) s
GROUP BY userID

SQL Fiddle DEMO