Question

我有一个名为Scores的表，其中包含以下列：id，player_id，value1，value2，value3和{{1 }}

该表格包含以下内容：

date

我正在尝试获取一个查询，该查询返回按“value1，value2，value3”中的值排序的每个玩家的最佳高分。 Value1是具有更高重要性，value2中等重要性和value3次要重要性的字段，例如：

+------+-----------+--------+--------+--------+------------+
|  id  | player_id | value1 | value2 | value3 |    date    |
+------+-----------+--------+--------+--------+------------+
|   1  |     1     |   10   |    0   |   0    | 2012-08-02 |
+------+-----------+--------+--------+--------+------------+
|   2  |     2     |   15   |    1   |   0    | 2012-08-03 |
+------+-----------+--------+--------+--------+------------+
|   3  |     3     |    9   |    0   |   0    | 2012-08-04 |
+------+-----------+--------+--------+--------+------------+
|   4  |     1     |   11   |    0   |   0    | 2012-08-05 |
+------+-----------+--------+--------+--------+------------+
|   5  |     2     |   16   |    2   |   0    | 2012-08-06 |
+------+-----------+--------+--------+--------+------------+
|   6  |     2     |   15   |    0   |   0    | 2012-08-07 |
+------+-----------+--------+--------+--------+------------+

我需要的查询的预期结果是：

value1 = 15                              value1 = 15
value2 = 1       is greater than ->      value2 = 0
value3 = 0                               value3 = 1

我正在尝试 MAX ， DISTINCT ， GROUP BY 和子查询，但我没有得到正确的结果。基本上它是下一个查询，但选择每个“组”的第一行：

+------+-----------+--------+--------+--------+------------+
|  id  | player_id | value1 | value2 | value3 |    date    |
+------+-----------+--------+--------+--------+------------+
|   5  |     2     |   16   |    2   |   0    | 2012-08-06 |
+------+-----------+--------+--------+--------+------------+
|   4  |     1     |   11   |    0   |   0    | 2012-08-05 |
+------+-----------+--------+--------+--------+------------+
|   3  |     3     |    9   |    0   |   0    | 2012-08-04 |
+------+-----------+--------+--------+--------+------------+

------ 编辑1 -------

eggyal的回答运作正常，但也许，表现不太好。我需要针对大型数据库对其解决方案进行基准测试，以检查响应时间。

我有一个想法（和可能的解决方案）。解决方案包括添加新的布尔列，其中说明该得分是否是该玩家的最佳得分。这样我需要检查当我将新分数添加到数据库中时，新分数是否优于该分区的最佳旧分数，如果是，我需要在旧的最佳分数中将该标记标记为假，并且在新的分数。这为我提供了一种直接检索每个玩家最佳得分的方法（简单查询，如SELECT id, player_id, value1, value2, value3 FROM scores ORDER BY value1 DESC, value2 DESC, value3 DESC）。

------ 编辑2 -------

weicap的回答是最快的解决方案。我不知道为什么，但他的查询比 eggyal的查询快两倍。

------ 编辑3 ------- 我错了，如果查询先前被缓存，weicap的查询会更快，如果不是查询需要十秒或更长时间。在变化中，weicap的答案总是需要300-400ms而不是80.000行。

Answer 1

对于每个value，您都可以获得groupwise maximum：

SELECT * FROM Scores NATURAL JOIN (
  SELECT player_id, value1, value2, MAX(value3) value3 FROM Scores NATURAL JOIN (
  SELECT player_id, value1, MAX(value2) value2         FROM Scores NATURAL JOIN (
  SELECT player_id, MAX(value1) value1                 FROM Scores
    GROUP BY player_id) t
    GROUP BY player_id) t
    GROUP BY player_id) t
ORDER BY value1 DESC, value2 DESC, value3 DESC

在sqlfiddle上查看。

Answer 2

你可以试试这个

SELECT player_id,
  (SELECT value1
   FROM Scores b where a.player_id=b.player_id  ORDER BY value1 DESC, value2 DESC, value3 DESC limit 1) as value1,
  (SELECT value2
   FROM Scores b where a.player_id=b.player_id  ORDER BY value1 DESC, value2 DESC, value3 DESC limit 1) as value2,
  (SELECT value3
   FROM Scores b where a.player_id=b.player_id  ORDER BY value1 DESC, value2 DESC, value3 DESC limit 1) as value3

FROM Scores a GROUP BY player_id order by value1 DESC, value2 DESC, value3 DESC

或类似

SELECT * FROM Scores a 

where id =(SELECT id
   FROM Scores b where a.player_id=b.player_id  ORDER BY value1 DESC, value2 DESC, value3 DESC limit 1)

GROUP BY player_id order by value1 DESC, value2 DESC, value3 DESC

Answer 3

尝试在(player_id, value1, value2, value3)上添加索引，然后在此查询中添加：

SELECT
    s.*
FROM 
        Scores AS s
    JOIN
        ( SELECT DISTINCT
              player_id
          FROM 
              Scores
        ) AS p
      ON s.id =
         ( SELECT
               id
           FROM 
               Scores AS b
           WHERE
               b.player_id = p.player_id
           ORDER BY
               value1 DESC, value2 DESC, value3 DESC
           LIMIT 1
         ) 
ORDER BY
    s.value1 DESC, s.value2 DESC, s.value3 DESC ;

Answer 4

你的实际得分是：1000,1510,900等......你明白了吗？它就像十进制数字，其中单个数字的位置很重要。您可以将3个值转换为单个值以进行分组，您可以在运行中（在查询中右侧）进行估计，也可以预先计算它（在将其写入表之前）。

Answer 5

您使用的是哪种语言（SQL除外）？如果SQL可以对它进行排序，那将是最简单的，但我不认为这是可能的。如果您使用的是PHP，那么您可以将它放在for循环中，为数组添加索引，例如'bestScore'，然后单独检查每个分数，如下所示：

//Extract Data Here
for($outI=0;$outI<count($scores);$outI++){
    $scores[$outI]['bestScore'] = 0;
    for($innI=0;$innI<=3;$innI++){
        if ($scores[$outI]['value' . $innI+1] > $scores[$outI]['bestScore'])
            $scores[$outI]['bestScore'] = $scores[$outI]['value' . $innI+1];
    }
    echo 'The best score for ' . $scores[$outI]['player_id'] . ' was ' . $scores[$outI]['bestScore'] . '.<br />';
}

如果按预期工作，则应列出每位玩家的最佳分数。

Answer 6

假设你的最大疼痛可以是16，试试这个，

Select Scores.* from Scores, (SELECT player_id,max(17*17*value1+17*value2+value3) 
as max_score  FROM Scores group by player_id)t where 
(17*17*value1+17*value2+value3) = t.max_score and Scores.player_id=t.player_id

Answer 7

SELECT * FROM (
SELECT id, player_id, value1, value2, value3, `date`
   FROM scores
   ORDER BY value1 DESC, value2 DESC, value3 DESC
) x 
GROUP BY player_id
order by value1 DESC, value2 DESC, value3 DESC

选择每位玩家的最佳得分

7 个答案: