Question

如果可能，我想只通过一个查询获取结果集我有这样的表

    ------------------------------
    user_id | activity_id | score 
    ------------------------------
        1   |      1      |  100
    ------------------------------
        1   |      1      |  50
    ------------------------------
        1   |      2      |  20
    ------------------------------
        1   |      3      |  10
    ------------------------------
        1   |      3      |  50
    ------------------------------
        2   |      1      |  300
    ------------------------------
        3   |      3      |  10
    ------------------------------
        3   |      2      |  40
    ------------------------------

我需要选择每个用户，并在每项活动中获得所有高分的总和。例如，结果集应该是这样的：

    ------------------------------
    user_id | score 
    ------------------------------
        1   |  170
    ------------------------------
        2   |  300
    ------------------------------
        3   |  50
    ------------------------------

Answer 1

要获得每个用户/活动对的最高分，您可以使用以下查询：

select user_id, activity_id, max(score) as highscore
from t
group by user_id, activity_id;

要为给定用户添加这些内容，您可以将其作为子查询并执行另一个聚合：

select user_id, sum(highscore)
from (select user_id, activity_id, max(score) as highscore
      from t
      group by user_id, activity_id
     ) t
group by user_id;

想要执行一个复杂的Mysql查询

1 个答案: