sql - 使用 unpivot 函数的 SQL 服务器

Question

您将如何使用 SQL 获得以下输出？

 Type:  Value  Type2       Value2
    p_01    1     ofpk_01     1
    p_02    2     ofpk_02     2
    p_03    3     ofpk_03     3

表结构

 create table test(p_01     int,
                   p_02     int,
                   p_03     int,
                   ofpk_01  int,
                   ofpk_02  int,
                   ofpk_03  int)

SQL小提琴链接

这可以通过 unpivot 功能实现吗？这是我到目前为止所得到的：

Answer 1

另一种解决方案是使用CROSS APPLY：

SELECT  ca.*
FROM    dbo.Test x
CROSS APPLY
(
    SELECT 'p_01' AS Type1, x.p_01 AS Value1, 'ofpk_01' AS Type2, x.ofpk_01 AS Value2 UNION ALL
    SELECT 'p_02' AS Type1, x.p_02 AS Value1, 'ofpk_02' AS Type2, x.ofpk_02 AS Value2 UNION ALL
    SELECT 'p_03' AS Type1, x.p_03 AS Value1, 'ofpk_03' AS Type2, x.ofpk_03 AS Value2
) ca;

SQL Fiddle

或者如果 2008+ 这可以缩短为

SELECT  ca.*
FROM    dbo.Test x
CROSS APPLY
(VALUES

    ('p_01', x.p_01, 'ofpk_01', x.ofpk_01),
    ('p_02', x.p_02, 'ofpk_02', x.ofpk_02),
    ('p_03', x.p_03, 'ofpk_03', x.ofpk_03)
) ca(Type1, Value1, Type2, Value2);

SQL Fiddle

Answer 2

我不认为你可以用unpivot. 我认为您必须执行以下操作：

Select
    'p_01' type,
    p_01 value,
    'ofpk_01' type2,
    ofpk_01 value2
From
    test
Union All
Select
    'p_02',
    p_02,
    'ofpk_02',
    ofpk_02
From
    test
Union All
Select
    'p_03',
    p_03,
    'ofpk_03',
    ofpk_03
From
    test

Example Fiddle