Question

我正在研究一些我从工作中获得的数据，并且我试图提出一个查询，让我的生活变得更加轻松（我花时间在mysql上导入这些数据。）

我有一堆样品在不同时间有不同的值（面积）（有点像钟形曲线），所以我需要做的就是在最大峰值和每个峰值（面积）之前加上每个峰值（面积）在每个样品的最大峰值（总共两列）之后。这项任务听起来非常简单，但我很难想出有效的水上运动。

我想出了类似的东西，但问题是我不能在where子句中“group by”，因为子查询中有多行返回，所以我无法比较其中的值样本。我尝试了几种不同的方法，但没有一种方法可以去任何地方。任何帮助将不胜感激。

SELECT Sample_name, sum(per_area) As '% area'/*For the areas before the peak.*/
FROM W_data.SEC_results
Where retention between /*retention =  time */
0 
AND 
(( select retention
from  W_data.SEC_results
where per_area = ( 
select max(per_area)
from W_data.SEC_results /* select the largest area in the entire set, instead of a specific samples */
)))
group by vial;

表：

+----------------------------------+------+-------------+----------+
| Sample_name                      | vial | retention   | per_area |
+----------------------------------+------+-------------+----------+
| a                                | 74   | 14.146      |   0.08   |
| a                                | 74   | 16.624      |  99.79   |
| a                                | 74   | 20.343      |   0.13   |
| b                                | 75   | 12.438      |   0.16   |
| b                                | 75   | 13.653      |   1.85   |
| b                                | 75   | 16.588      |  97.95   |
| b                                | 75   | 20.316      |   0.04   |

+-------------+----------------+-------------+
| sample_name | Area( before)  |Area (after) |  
+-------------+----------------+-------------+
| a           | 0.08           |   0.13      |
| b           | 2.01           |   0.04      |

Answer 1

逻辑是： - 首先找到所有样品瓶的最大per_area

select vial,max(per_area) maxarea from sec_results group by vial

| 74 | 99.79 |

| 75 | 97.95 |

然后为他们找到相应的时间

select sr.vial,sr.time,mt.maxarea from sec_results sr,
    (select vial,max(per_area) maxarea from sec_results group by vial) mt

| 74 | 16.624 | 99.79 |

| 75 | 16.588 | 97.95 |

并将这些时间的值分别加以总和。

select a.sample_name,sum(if(a.time<temp.time,a.per_area,0)) Area_before,
       sum(if(a.time>temp.time,a.per_area,0)) Area_after 
from sec_results a, (select sr.vial,sr.time,mt.maxarea 
                     from sec_results sr,(select vial,max(per_area) maxarea 
                                          from sec_results 
                                          group by vial) mt
                     where sr.vial = mt.vial
                     and sr.per_area = mt.maxarea
                    ) temp
where a.vial = temp.vial
group by a.vial,a.sample_name;

Answer 2

刚刚为此感兴趣。试图想出一种方法来避免在SUM中使用IF来获得正确的结果。

管理过它，但并不认为它有效。但是我已经付出了努力，我认为我会把它们放在这里只是为了兴趣。

第一种方式，加入一对子选择，每个子选择在之前或之后获得总和： -

SELECT DISTINCT a.sample_name, b.AreaBefore, c.AreaAfter
FROM sec_results a
LEFT OUTER JOIN (
    SELECT sr.vial, SUM(sr_max.per_area) AS AreaBefore
    FROM sec_results sr
    INNER JOIN (
        SELECT vial, max(per_area) AS maxarea 
        FROM sec_results 
        GROUP BY vial) Sub1
    ON sr.vial = Sub1.vial
    AND sr.per_area = Sub1.maxarea
    INNER JOIN sec_results sr_max
    ON sr.vial = sr_max.vial
    AND sr.retention > sr_max.retention
    GROUP BY vial
) b
ON a.vial = b.vial
LEFT OUTER JOIN (
    SELECT sr.vial, SUM(sr_max.per_area) AS AreaAfter
    FROM sec_results sr
    INNER JOIN (
        SELECT vial, max(per_area) AS maxarea 
        FROM sec_results 
        GROUP BY vial) Sub1
    ON sr.vial = Sub1.vial
    AND sr.per_area = Sub1.maxarea
    INNER JOIN sec_results sr_max
    ON sr.vial = sr_max.vial
    AND sr.retention < sr_max.retention
    GROUP BY vial
) c
ON a.vial = c.vial

第二种方式，即使用子选择来获取每条记录的前（或后）记录的总和，然后将其与子选择相加以获得最大记录。

SELECT a_sec_result.vial, a_sec_result.sample_name, area_before.area AS AreaBefore, area_after.area AS AreaAfter
FROM (
    SELECT sr.vial, sr.sample_name, sr.retention
    FROM sec_results sr
    INNER JOIN (
        SELECT vial, sample_name, max(per_area) AS maxarea 
        FROM sec_results 
        GROUP BY vial, sample_name
    ) max_area_sub
    ON sr.vial = max_area_sub.vial
    AND sr.sample_name = max_area_sub.sample_name
    AND sr.per_area = max_area_sub.maxarea 
) a_sec_result
INNER JOIN(
    SELECT sr.vial, sr.retention, SUM(sr2.per_area) AS area
    FROM sec_results sr
    LEFT OUTER JOIN sec_results sr2
    ON sr.vial = sr2.vial
    AND sr.retention > sr2.retention
    GROUP BY sr.vial, sr.retention
) area_before
ON a_sec_result.vial = area_before.vial
AND a_sec_result.retention = area_before.retention
INNER JOIN(
    SELECT sr.vial, sr.retention, SUM(sr2.per_area) AS area
    FROM sec_results sr
    LEFT OUTER JOIN sec_results sr2
    ON sr.vial = sr2.vial
    AND sr.retention < sr2.retention
    GROUP BY sr.vial, sr.retention
) area_after
ON a_sec_result.vial = area_after.vial
AND a_sec_result.retention = area_after.retention

两者都应该给出正确的结果。

mysql聚合函数问题（如何在同一组中的特定值之前和之后添加值）

2 个答案: