SQL复杂动态Pivoting 2

Question

嗨,我在SQL Server中尝试下表的透视

REFID | COL1 | COL2 | Sequence
1       abc    cde     1
1       lmn    rst     2
1       kna    asg     3
2       als    zkd     2
2       zpk    lad     1

我希望输出为

        REFID | 1COL1 | 2COL1 | 3COL1 |1COL2|2COL2|3COL2
           1    abc     lmn      kna    cde   rst   asg
           2    zpk     als      null   lad   zkd   null

原始表中的列数是已知的,但行数未知.任何人都可以帮忙

Answer 1

如果要将sequence数字作为列名称的一部分包含在内,则仍需要首先取消对列col1和col2列的拆分,然后应用数据透视表.不同之处在于,您将连接sequence数字与在unpivot过程中创建的列名称连接.

对于已知数量的值,查询将是:

select REFID, 
    [1col1], [2col1], [3col1],
    [1col2], [2col2], [3col2]
from 
(
    select REFID, 
        col = cast(Sequence as varchar(10))+ col, value
    from yourtable
    cross apply
    (
        select 'COL1', col1 union all
        select 'COL2', col2
    ) c (col, value)
) d
pivot
(
    max(value)
    for col in ([1col1], [2col1], [3col1],
                [1col2], [2col2], [3col2])
) piv
order by refid;

然后,如果您有一个未知的数字,动态SQL版本将是:

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

select @cols = STUFF((SELECT ',' + QUOTENAME(cast(Sequence as varchar(10))+ col) 
                    from yourtable
                    cross apply
                    (
                        select 'Col1', 1 union all
                        select 'Col2', 2
                    ) c(col, so)
                    group by Sequence, col, so
                    order by  so, sequence
                    FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query = 'SELECT refid, ' + @cols + ' 
            from 
            (
               select REFID, 
                    col = cast(Sequence as varchar(10))+ col, value
                from yourtable
                cross apply
                (
                    select ''COL1'', col1 union all
                    select ''COL2'', col2
                ) c (col, value)
            ) x
            pivot 
            (
                max(value)
                for col in (' + @cols + ')
            ) p 
            order by refid'

execute sp_executesql @query;