在Oracle中使用聚合旋转/透视表

Question

我想在Oracle 11g中旋转一个表.pivot选项需要聚合.这是我原来的表:

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'

在旋转之后,表格应如下所示:

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,正如您所看到的,分组应该在项目列上进行.没有值需要折叠或计算.仅仅轮换是必要的.那么,枢轴选择正确的做法是什么？

Answer 1

是的,我想是这样.使用MAX聚合很容易做这样的枢轴:

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

否则你必须在最大聚合内部做一个case语句.像这样:

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

这几乎和做的一样PIVOT.但我宁愿做PIVOT在CASE WHEN MAX..