如何将单行SQL结果转换为多行?

问题描述：

我正在 SSMS 2008 R2 中开发一个仅返回一行的 T-SQL 查询.但问题是在这一行中有四个字段，我希望它们是唯一的行.例如，我的输出行如下所示:

I am developing a T-SQL query in SSMS 2008 R2 which returns one line only. But the problem is that in this one line there are four fields which I instead want to be unique rows. For example, my output line looks like:

Col. 1   Col. 2   Col. 3   Col. 4
xxxx     yyyy     zzzz     aaaa

相反，我希望它看起来像:

Instead, I want this to look like:

Question    Answer
Col. 1      xxxx
Col. 2      yyyy
Col. 3      zzzz
Col. 4      aaaa

我已尝试为此使用 UNPIVOT 运算符，但它没有执行上述操作.我怎样才能做到这一点?

I have tried using the UNPIVOT operator for this, but it is not doing the above. How can I achieve this?

答

您应该能够使用取消透视:

这是一个静态数据透视表，您可以在其中对列的值进行硬编码:

Here is a static pivot where you hard code in the values of the columns:

create table t1
(
    col1 varchar(5),
    col2 varchar(5),
    col3 varchar(5),
    col4 varchar(5)
)

insert into t1 values ('xxxx', 'yyyy', 'zzzz', 'aaaa')

select question, answer
FROM t1
unpivot
(
    answer
    for question in (col1, col2, col3, col4)
) u

drop table t1

这是带有演示的 SQL Fiddle.

但您也可以使用动态逆枢轴:

but you can also use a Dynamic Unpivot:

DECLARE @cols AS NVARCHAR(MAX),
    @query  AS NVARCHAR(MAX);

select @cols = stuff((select ','+quotename(C.name)
         from sys.columns as C
         where C.object_id = object_id('t1') and
               C.name like 'Col%'
         for xml path('')), 1, 1, '')

set @query = 'SELECT question, answer
            from t1
            unpivot 
            (
               answer
               for question in (' + @cols + ')
            ) p '

execute(@query)

如何将单行SQL结果转换为多行?

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