如何将垂直数据转换为具有可变行长的水平数据SQL？_Sql_Sql Server 2005_Pivot_Unpivot

如何将垂直数据转换为具有可变行长的水平数据SQL？

sql sql-server-2005

如何将垂直数据转换为具有可变行长的水平数据SQL？,sql,sql-server-2005,pivot,unpivot,Sql,Sql Server 2005,Pivot,Unpivot,好的，我有下表。 Name ID Website Aaron | 2305 | CoolSave1 Aaron | 8464 | DiscoWorld1 Adriana | 2956 | NewCin1 Adriana | 5991 | NewCin2 Adriana | 4563 NewCin3 我想将其转换为以下方式 Adriana | 2956 | NewCin1 | 5991 | NewCin2 | 4563 | NewCin3

好的，我有下表。

Name    ID  Website

Aaron | 2305 |  CoolSave1


Aaron | 8464 |  DiscoWorld1


Adriana |   2956 |  NewCin1


Adriana |   5991 |  NewCin2


Adriana | 4563  NewCin3

我想将其转换为以下方式

Adriana  |  2956 |  NewCin1 |   5991 |  NewCin2 | 4563  | NewCin3


Aaron | 2305 | CoolSave1 |  8464 |  DiscoWorld | NULL | NULL

如您所见，我正试图从第一个表中获取第一个名称，并将与该名称相关联的所有ID/网站列成一行。问题是，可能有大量网站与每个名称关联。为了处理这个问题，我只想创建一个表，表中的字段数与max行项目相同，然后对于后续的行项目，在没有足够数据的地方插入一个NULL。

为了得到结果，需要对数据应用UNPIVOT和PIVOT函数。UNPIVOT将获取列（ID、website）并将它们转换为行，完成后，您可以将数据转回到列中

UNPIVOT代码类似于以下代码：

select name,
  col+'_'+cast(col_num as varchar(10)) col,
  value
from
(
  select name, 
    cast(id as varchar(11)) id, 
    website,
    row_number() over(partition by name order by id) col_num
  from yt
) src
unpivot
(
  value
  for col in (id, website)
) unpiv;

看。这就产生了一个结果：

|    NAME |       COL |       VALUE |
-------------------------------------
|   Aaron |      id_1 |        2305 |
|   Aaron | website_1 |   CoolSave1 |
|   Aaron |      id_2 |        8464 |
|   Aaron | website_2 | DiscoWorld1 |

如您所见，我在取消PIVOT之前对数据应用了一个

row\u number（）

，该行号用于生成新的列名。UNPIVOT中的列也必须是相同的数据类型，我在子查询中的

id

列上应用了

cast

，以便在透视之前将数据转换为

varchar

然后在枢轴中使用

col

值。数据解除锁定后，应用PIVOT函数：

select *
from
(
  select name,
    col+'_'+cast(col_num as varchar(10)) col,
    value
  from
  (
    select name, 
      cast(id as varchar(11)) id, 
      website,
      row_number() over(partition by name order by id) col_num
    from yt
  ) src
  unpivot
  (
    value
    for col in (id, website)
  ) unpiv
) d
pivot
(
  max(value)
  for col in (id_1, website_1, id_2, website_2, id_3, website_3)
) piv;

看

如果您的值数量有限或已知，则上述版本非常有效。但如果行数未知，则需要使用动态SQL生成结果：

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

select @cols = STUFF((SELECT ',' + QUOTENAME( col+'_'+cast(col_num as varchar(10))) 
                    from
                    (
                      select row_number() over(partition by name order by id) col_num
                      from yt
                    ) t
                    cross apply
                    (
                      select 'id' col union all
                      select 'website'
                    ) c
                    group by col, col_num
                    order by col_num, col
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query = 'SELECT name,' + @cols + ' 
            from 
            (
               select name,
                col+''_''+cast(col_num as varchar(10)) col,
                value
              from
              (
                select name, 
                  cast(id as varchar(11)) id, 
                  website,
                  row_number() over(partition by name order by id) col_num
                from yt
              ) src
              unpivot
              (
                value
                for col in (id, website)
              ) unpiv
            ) x
            pivot 
            (
                max(value)
                for col in (' + @cols + ')
            ) p '

execute(@query);

|    NAME | ID_1 | WEBSITE_1 | ID_2 |   WEBSITE_2 |   ID_3 | WEBSITE_3 |
------------------------------------------------------------------------
|   Aaron | 2305 | CoolSave1 | 8464 | DiscoWorld1 | (null) |    (null) |
| Adriana | 2956 |   NewCin1 | 4563 |     NewCin3 |   5991 |   NewCin2 |

看。两个版本都给出了结果：

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

select @cols = STUFF((SELECT ',' + QUOTENAME( col+'_'+cast(col_num as varchar(10))) 
                    from
                    (
                      select row_number() over(partition by name order by id) col_num
                      from yt
                    ) t
                    cross apply
                    (
                      select 'id' col union all
                      select 'website'
                    ) c
                    group by col, col_num
                    order by col_num, col
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query = 'SELECT name,' + @cols + ' 
            from 
            (
               select name,
                col+''_''+cast(col_num as varchar(10)) col,
                value
              from
              (
                select name, 
                  cast(id as varchar(11)) id, 
                  website,
                  row_number() over(partition by name order by id) col_num
                from yt
              ) src
              unpivot
              (
                value
                for col in (id, website)
              ) unpiv
            ) x
            pivot 
            (
                max(value)
                for col in (' + @cols + ')
            ) p '

execute(@query);

|    NAME | ID_1 | WEBSITE_1 | ID_2 |   WEBSITE_2 |   ID_3 | WEBSITE_3 |
------------------------------------------------------------------------
|   Aaron | 2305 | CoolSave1 | 8464 | DiscoWorld1 | (null) |    (null) |
| Adriana | 2956 |   NewCin1 | 4563 |     NewCin3 |   5991 |   NewCin2 |