Question

我需要一些查询设计方面的帮助。我有一个有很多行的表（它需要在一个表中）。

Table name: 201201
columns = code, batch, value, volume
rows =    301,  2920,  100,   2000
          301,  3192,  40,    800
          302,  6479,  230,   3100
          303,  4930,  20,    50
          303,  3920,  60,    95

我怎样才能拉出结果，以便以这种方式呈现：

code, batches, value, volume
301,  2,       140,   2800
302,  1,       230,   3100
303,  2,       80,    145

我在使用multiplie表时已经这样做了，但是当所有行都在同一个表中时无法使它工作。

我设法通过此查询获取批次计数和mrdr

SELECT DISTINCT(`201201`.code), count(DISTINCT(z.batch)) as batches
FROM `201201` 
LEFT JOIN `201201` AS z ON `201201`.code = z.code
GROUP BY `201201`.code

但后来我被困住了。提前谢谢。

新问题！好的，所以在同一个表中我有一个风险列，其中包含每个批次的浮点数：

    Table name: 201201
columns = code, batch, value, volume, risk
rows =    301,  2920,  100,   2000,   0.3
          301,  3192,  40,    800,    0.2
          302,  6479,  230,   3100,   0.8
          303,  4930,  20,    50,     0.8
          303,  3920,  60,    95,     1

我想要的是将风险乘以每行的值，然后按照代码求和，就像这样。

code, batches, value, volume, risk
301,  2,       140,   2800,   38

38来自，0.3 * 100 + 0.2 * 40。代码302和303也是如此。

Answer 1

为什么在没有加入的情况下你可以加入？希望这会有所帮助：

SELECT `code`, 
        COUNT(`Batch`) as Batches,
        SUM(`Value`) as TotalValue,
        SUM(`Volume`) as TotalVolume,
        SUM(`Value` * `Risk`) as TotalRisk  -- I'm not sure if this works
FROM `201201`
GROUP BY `code`

如果上述方法不起作用，请尝试自我加入：

SELECT a.`code`, 
        COUNT(a.`Batch`) as Batches,
        SUM(a.`Value`) as TotalValue,
        SUM(a.`Volume`) as TotalVolume,
        SUM(b.`SubRisk`) as TotalRisk
FROM `201201` a INNER JOIN 
            (
                SELECT c.`code`, (c.`Value` * c.`Risk`) as SubRisk
                FROM `201201` c
            ) b ON a.`Code` = b.`Code`
GROUP BY `code`

Answer 2

看起来你正在添加其他值..？

SELECT code, count(batch) as batches, sum(value) as values, sum(volume ) as volumes
FROM `201201` 
GROUP BY `201201`.code

Answer 3

SELECT Code, Count(Batch), Sum(Value), Sum(Count) FROM 201201 GROUP BY Code

Sql只从一个表连接

3 个答案: