在Oracle中通过汇总来旋转/旋转表 [英] Rotate/pivot table with aggregation in Oracle

问题描述

我想在Oracle 11g中旋转一个表.枢纽选项需要汇总. 这是我的原始表格:

I'd like to rotate a table in Oracle 11g. The pivot option requires an aggregation. This is my original table:

project | attribute | value
===========================
'cust1' | 'foo'     | '4'
'cust2' | 'bar'     | 'tbd'
'cust3  | 'baz'     | '2012-06-07'
'cust1' | 'bar'     | 'tdsa'
'cust4' | 'foo'     | '22'
'cust4' | 'baz'     | '2013-01-01'

旋转后，表格应如下所示:

After pivoting, the table should look like this:

project | foo | bar | baz
=========================
'cust1' | '4' |'tdba'| NULL
'cust2' | NULL|'tbd' | NULL
'cust3' | NULL| NULL | '2012-06-07'
'cust4' | '22'| NULL | '2013-01-01'

现在，如您所见，分组应该在项目列上进行.无需折叠或计算值.只需旋转即可. 那么，枢轴选择正确的事情了吗?

Now, as you can see, the grouping should happen over the project column. No values need to be collapsed or calcucation. A mere rotation is necessary. So, is the pivot select the right thing to do?

推荐答案

是的.使用MAX聚合可以很容易地进行这样的数据透视:

Yes I think so. It is easy to do a pivot like this with a MAX aggregate:

SELECT
    *
FROM
(
    SELECT
        project,
        attribute,
        value
    FROM
        table1
) AS SourceTable
PIVOT
(
    MAX(value)
    FOR attribute IN ([foo],[bar],[baz])
) AS pvt

否则，您必须在最大聚合内执行一个case语句.像这样:

Otherwise you have to do a case statement inside the a max aggregate. Like this:

SELECT
    MAX(CASE WHEN attribute='foo' THEN value ELSE NULL END) AS foo,
    MAX(CASE WHEN attribute='bar' THEN value ELSE NULL END) AS bar,
    MAX(CASE WHEN attribute='baz' THEN value ELSE NULL END) AS baz,
    project
FROM
    table1
GROUP BY
    project

这几乎与PIVOT相同.但是我更喜欢使用PIVOT而不是CASE WHEN MAX ..

This is almost the same thing as doing the PIVOT. But I would prefer doing the PIVOT over the CASE WHEN MAX..

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