Question

我正在尝试计算来自数据库的值列表的差异。我想用php或mysql实现它，但我不知道如何继续。我有一个名为player_scores的表。其中一行包含得分的目标。

实施例

pl_date         pl_scores
03/11/2014      18
02/11/2014      15
01/11/2014      10

我想回应一下在不同日期比赛中进球的差异。

Ex:
pl_date       pl_scores    diff
03/11/2014     18          +3
02/11/2014     15          +5
01/11/2014     10          no diff

如何获得所需的结果？

Answer 1

您似乎想要将分数与前一行的分数进行比较。

如果使用获得最大pl_date且小于当前行的pl_date的子查询完成，则可能最简单，然后将该子查询的结果反馈到player_scores表以获取每个日期的详细信息： - < / p>

SELECT ps1.pl_date, ps1.pl_scores, IF(ps2.pl_date IS NULL OR ps1.pl_scores = ps1.pl_scores, 'no diff', ps1.pl_scores - ps1.pl_scores) AS diff
FROM
(
    SELECT ps1.pl_date, MAX(ps2.pl_date) prev_date
    FROM player_scores ps1
    LEFT OUTER JOIN player_scores ps2
    ON ps1.pl_date > ps2.pl_date
    GROUP BY ps1.pl_date
) sub0
INNER JOIN player_scores ps1
ON sub0.pl_date = ps1.pl_date
LEFT OUTER JOIN player_scores ps2
ON sub0.prev_date = ps2.pl_date

还有其他方法可以做到这一点（例如，使用变量来处理有序子查询的结果，将每一行与存储在前一行变量中的值进行比较）

Answer 2

select *,
 coalesce(
 (SELECT concat(IF(t1.pl_scores>t2.pl_scores,'+',''),(t1.pl_scores-t2.pl_scores))
     FROM tableX t2 WHERE t2.pl_date<t1.pl_date ORDER BY t2.pl_date DESC LIMIT 1)
 , 'no data' ) as diff
FROM tableX t1
WHERE 1
order by t1.pl_date DESC

Answer 3

您可以使用两个查询，一个用于获取要在比较中使用的值（在下面的示例中是较小的分数），第二个用于获取具有差异的专用列的记录：

SELECT MIN(pl_scores);

SELECT pl_date, pl_scores, (pl_scores - minScore) as diff FROM player_scores;

或者，使用事务（一个查询执行php端）：

START TRANSACTION;

SELECT MIN(Importo) FROM Transazione INTO @min;

SELECT Importo, (Importo - @min) as diff FROM Transazione;

Answer 4

SELECT score FROM TABLE WHERE DATE = TheDateYouWant 

$score = $data['score']; 

 SELECT score FROM TABLE WHERE date = dateYouWant
 $difference = $score - $data['score'];

这样的东西？

如何计算来自mysql中同一行的值之间的差异

4 个答案: