像这样：

SELECT
        user_id,
        sum( IF(a.`action` = 'a', 0.6, 0.4) * 1000 / TIMESTAMPDIFF(second, a.timestamp, now()) ),

    FROM actions a

    group by user_id

如果我理解正确，你只需要一个普通的 GROUP BY . 你可以 JOIN 重量。使用 ORDER BY 排序。假设你的table action_user .

SELECT au.`user_id`,
       sum(a.`weight` / (current_timestamp() - au.`timestamp`)) `score`
       FROM `action_user` au
            INNER JOIN (SELECT 'A' `action`,
                               .6 `weight`
                        UNION ALL
                        SELECT 'B' `action`,
                               .4 `weight`) a
                       ON a.`action` = au.`action`
       GROUP BY au.`user_id`
       ORDER BY 2 DESC;

但我不确定你的配方。这是一些非常小的数字。也许可以根据需要改变。