Question

首先，我想为 n + 1st Query-too-complex-question道歉。

自I've been told that my dtabase deserves normalisation以来，我尝试使用规范化设置做同样的事情。但是，Access现在抱怨过于复杂的查询。

我想做什么：起点是一个产生字段Item ID, Difference in attribute 1, Group of attribute 1, Difference in Attribute 2, Group of attribute 2,...的查询（大约10.000行，查询只是要比较的两个数据集的等值连接）。对于每个属性，我想绘制一个直方图，显示该属性的差异分布。实际上，我想在一个画布中绘制两个直方图，其中一个约束为Group = 1。

我尝试了什么：

第一步是构建一个规范化查询（基于union s），产生列Item ID, attribute, difference, group。此查询产生大约100.000行。
下一步是绘制直方图。不幸的是，访问没有内置的直方图，所以我使用了一个xy图表，其数据源是一个查询，它是四个查询的并集，可以生成垃圾箱的角落。
由于我想绘制两个直方图，因此这个数据源查询union带有一个带有额外group = 1条件的自身副本。

所以我尝试了以下查询：

select bin, max(c), max(c2) from (
    -- collect the four corners of the first histogram
    select bin, cnt as c, 1 as c2, ord from (
        -- top right
        select
            cdbl(bin(difference, 0.1, -2, 2) + 0.05) AS bin,
            Count(bin) AS cnt,
            1 as ord
        FROM normalized_data
        WHERE difference Is Not Null
            and attribut='attibute_name'
            and difference between -2 and 2
        GROUP BY
            cdbl(bin(difference, 0.1, -2, 2) + 0.05)

        union all

        -- bottom right
        select
            cdbl(bin(difference, 0.1, -2, 2) + 0.05) AS bin,
            0 AS cnt,
            2 as ord
        FROM normalized_data
        WHERE difference Is Not Null
            and attribut='attibute_name'
            and difference between -2 and 2
        GROUP BY
            cdbl(bin(difference, 0.1, -2, 2) + 0.05)

        union all

        -- bottom left
        select
            cdbl(bin(difference, 0.1, -2, 2) - 0.05) AS bin,
            0 AS cnt,
            3 as ord
        FROM normalized_data
        WHERE difference Is Not Null
            and attribut='attibute_name'
            and difference between -2 and 2
        GROUP BY
            cdbl(bin(difference, 0.1, -2, 2) - 0.05)

        union all

        -- top left
        select
            cdbl(bin(difference, 0.1, -2, 2) - 0.05) AS bin,
            Count(bin) AS cnt,
            4 as ord
        FROM normalized_data
        WHERE difference Is Not Null
            and attribut='attibute_name'
            and difference between -2 and 2
        GROUP BY
            cdbl(bin(difference, 0.1, -2, 2) - 0.05)
        order by bin, ord asc
    ) 

    union all 

    -- connect the corners of the other one
    select bin, 1 as c, cnt as c2, ord from (
        select
            cdbl(bin(difference, 0.1, -2, 2) + 0.05) AS bin,
            Count(bin) AS cnt,
            1 as ord
        FROM normalized_data
        WHERE difference Is Not Null
            and attribut='attibute_name'
            and difference between -2 and 2
            AND (GR=1)
        GROUP BY
            cdbl(bin(difference, 0.1, -2, 2) + 0.05)
        union all
        select
            cdbl(bin(difference, 0.1, -2, 2) + 0.05) AS bin,
            0 AS cnt,
            2 as ord
        FROM normalized_data
        WHERE difference Is Not Null
            and attribut='attibute_name'
            and difference between -2 and 2
            AND (GR=1)
        GROUP BY
            cdbl(bin(difference, 0.1, -2, 2) + 0.05)
        union all
        select
            cdbl(bin(difference, 0.1, -2, 2) - 0.05) AS bin,
            0 AS cnt,
            3 as ord
        FROM normalized_data
        WHERE difference Is Not Null
            and attribut='attibute_name'
            and difference between -2 and 2
            AND (GR=1)
        GROUP BY
            cdbl(bin(difference, 0.1, -2, 2) - 0.05)
        union all
        select
            cdbl(bin(difference, 0.1, -2, 2) - 0.05) AS bin,
            Count(bin) AS cnt,
            4 as ord
        FROM normalized_data
        WHERE difference Is Not Null
            and attribut='attibute_name'
            and difference between -2 and 2
            AND (GR=1)
        GROUP BY
            cdbl(bin(difference, 0.1, -2, 2) - 0.05)
        order by bin, ord asc
    )
) 
group by bin, ord 
order by bin, ord asc

计算两个最里面的union，以及中间级别的两个查询。但是，当我尝试计算最外面的union时，访问会抱怨查询的复杂性（在非标准化查询中没有发生）

问题：我有机会解决这个问题吗？

备注：引入了中间步骤以简化自动代码生成。去除并不能解决问题。

编辑：表中的内容：根据要求，我将添加一些有关表中存储内容和查询内容的信息。我有两张桌子

create table A (
    id integer not null primary key,
    [attribute 1] integer,
    [attribute 2] integer,
    ...
)

create table B (
    id integer not null primary key,
    [attribute 1] integer,
    [attribute 2] integer,
    ...
)

和查询differences抱怨他们：

select
    id,
    A.[attribute 1] - B.[attribute 1] as [delta 1],
    ...
from A
inner join B on A.id = B.id

我知道这个非标准化的数据模型是糟糕的设计，但我不是设计模型的负责人。这就是为什么已经建立了一个查询normalized_data，它可以从differences中取消数据的显示：

select
    id,
    'attribute 1' as attribute,
    delta 1 as difference
from differences
union all
select
    id,
    'attribute 2' as attribute,
    delta 2 as difference
from differences
union all
...

请注意，如果使用differences中的非标准化数据作为输入，或使用来自normalized_data的不透露数据，则上述查询的代码不会发生太大变化。

跟进：规范化后，Access认为查询过于复杂

0 个答案: