Pivot是SQL操作符之一，用于将输出中的唯一数据从一列转换为多列。这也意味着将行转换为列(旋转表)。让我们考虑这张桌子，

如果我想根据每个客户的产品类型(扬声器、眼镜、耳机)过滤这些数据，那么使用Pivot操作符。

Select CustmerName, Speaker, Glass, Headset  
from TblCustomer  
   Pivot  
    (  
     Sum(Price) for Product in ([Speaker],[Glass],[Headset])  
    ) as PivotTable 

如果您使用的是SQL Server 2005+，那么您可以使用PIVOT函数将数据从行转换为列。

听起来，如果星期是未知的，您将需要使用动态sql，但最初使用硬编码版本更容易看到正确的代码。

首先，这里有一些快速的表定义和数据:

CREATE TABLE yt 
(
  [Store] int, 
  [Week] int, 
  [xCount] int
);
    
INSERT INTO yt
(
  [Store], 
  [Week], [xCount]
)
VALUES
    (102, 1, 96),
    (101, 1, 138),
    (105, 1, 37),
    (109, 1, 59),
    (101, 2, 282),
    (102, 2, 212),
    (105, 2, 78),
    (109, 2, 97),
    (105, 3, 60),
    (102, 3, 123),
    (101, 3, 220),
    (109, 3, 87);

如果你的值是已知的，那么你将硬编码查询:

select *
from 
(
  select store, week, xCount
  from yt 
) src
pivot
(
  sum(xcount)
  for week in ([1], [2], [3])
) piv;

参见SQL Demo

然后如果你需要动态生成周数，你的代码将是:

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

select @cols = STUFF((SELECT ',' + QUOTENAME(Week) 
                    from yt
                    group by Week
                    order by Week
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query = 'SELECT store,' + @cols + ' from 
             (
                select store, week, xCount
                from yt
            ) x
            pivot 
            (
                sum(xCount)
                for week in (' + @cols + ')
            ) p '

execute(@query);

参见SQL Demo。

动态版本生成应转换为列的周数列表。两者都给出了相同的结果:

| STORE |   1 |   2 |   3 |
---------------------------
|   101 | 138 | 282 | 220 |
|   102 |  96 | 212 | 123 |
|   105 |  37 |  78 |  60 |
|   109 |  59 |  97 |  87 |

你可以这样做:

SELECT * 
FROM yourTable
PIVOT (MAX(xCount) 
       FOR Week in ([1],[2],[3],[4],[5],[6],[7])) AS pvt

DEMO

我写了一个sp，这个sp对这个目的很有用，基本上这个sp对任何表进行枢轴化，并返回一个新的表，或者只返回一组数据，这是执行它的方式:

Exec dbo.rs_pivot_table @schema=dbo,@table=table_name,@column=column_to_pivot,@agg='sum([column_to_agg]),avg([another_column_to_agg]),',
        @sel_cols='column_to_select1,column_to_select2,column_to_select1',@new_table=returned_table_pivoted;

请注意，在参数@agg中，列名必须以'['结尾，参数必须以逗号'，'

SP

Create Procedure [dbo].[rs_pivot_table]
    @schema sysname=dbo,
    @table sysname,
    @column sysname,
    @agg nvarchar(max),
    @sel_cols varchar(max),
    @new_table sysname,
    @add_to_col_name sysname=null
As
--Exec dbo.rs_pivot_table dbo,##TEMPORAL1,tip_liq,'sum([val_liq]),sum([can_liq]),','cod_emp,cod_con,tip_liq',##TEMPORAL1PVT,'hola';
Begin

    Declare @query varchar(max)='';
    Declare @aggDet varchar(100);
    Declare @opp_agg varchar(5);
    Declare @col_agg varchar(100);
    Declare @pivot_col sysname;
    Declare @query_col_pvt varchar(max)='';
    Declare @full_query_pivot varchar(max)='';
    Declare @ind_tmpTbl int; --Indicador de tabla temporal 1=tabla temporal global 0=Tabla fisica

    Create Table #pvt_column(
        pivot_col varchar(100)
    );

    Declare @column_agg table(
        opp_agg varchar(5),
        col_agg varchar(100)
    );

    IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(@table) AND type in (N'U'))
        Set @ind_tmpTbl=0;
    ELSE IF OBJECT_ID('tempdb..'+ltrim(rtrim(@table))) IS NOT NULL
        Set @ind_tmpTbl=1;

    IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(@new_table) AND type in (N'U')) OR 
        OBJECT_ID('tempdb..'+ltrim(rtrim(@new_table))) IS NOT NULL
    Begin
        Set @query='DROP TABLE '+@new_table+'';
        Exec (@query);
    End;

    Select @query='Select distinct '+@column+' From '+(case when @ind_tmpTbl=1 then 'tempdb.' else '' end)+@schema+'.'+@table+' where '+@column+' is not null;';
    Print @query;

    Insert into #pvt_column(pivot_col)
    Exec (@query)

    While charindex(',',@agg,1)>0
    Begin
        Select @aggDet=Substring(@agg,1,charindex(',',@agg,1)-1);

        Insert Into @column_agg(opp_agg,col_agg)
        Values(substring(@aggDet,1,charindex('(',@aggDet,1)-1),ltrim(rtrim(replace(substring(@aggDet,charindex('[',@aggDet,1),charindex(']',@aggDet,1)-4),')',''))));

        Set @agg=Substring(@agg,charindex(',',@agg,1)+1,len(@agg))

    End

    Declare cur_agg cursor read_only forward_only local static for
    Select 
        opp_agg,col_agg
    from @column_agg;

    Open cur_agg;

    Fetch Next From cur_agg
    Into @opp_agg,@col_agg;

    While @@fetch_status=0
    Begin

        Declare cur_col cursor read_only forward_only local static for
        Select 
            pivot_col 
        From #pvt_column;

        Open cur_col;

        Fetch Next From cur_col
        Into @pivot_col;

        While @@fetch_status=0
        Begin

            Select @query_col_pvt='isnull('+@opp_agg+'(case when '+@column+'='+quotename(@pivot_col,char(39))+' then '+@col_agg+
            ' else null end),0) as ['+lower(Replace(Replace(@opp_agg+'_'+convert(varchar(100),@pivot_col)+'_'+replace(replace(@col_agg,'[',''),']',''),' ',''),'&',''))+
                (case when @add_to_col_name is null then space(0) else '_'+isnull(ltrim(rtrim(@add_to_col_name)),'') end)+']'
            print @query_col_pvt
            Select @full_query_pivot=@full_query_pivot+@query_col_pvt+', '

            --print @full_query_pivot

            Fetch Next From cur_col
            Into @pivot_col;        

        End     

        Close cur_col;
        Deallocate cur_col;

        Fetch Next From cur_agg
        Into @opp_agg,@col_agg; 
    End

    Close cur_agg;
    Deallocate cur_agg;

    Select @full_query_pivot=substring(@full_query_pivot,1,len(@full_query_pivot)-1);

    Select @query='Select '+@sel_cols+','+@full_query_pivot+' into '+@new_table+' From '+(case when @ind_tmpTbl=1 then 'tempdb.' else '' end)+
    @schema+'.'+@table+' Group by '+@sel_cols+';';

    print @query;
    Exec (@query);

End;
GO

这是一个执行的例子:

Exec dbo.rs_pivot_table @schema=dbo,@table=##TEMPORAL1,@column=tip_liq,@agg='sum([val_liq]),avg([can_liq]),',@sel_cols='cod_emp,cod_con,tip_liq',@new_table=##TEMPORAL1PVT;

然后Select * From ##TEMPORAL1PVT将返回:

这是动态的# of weeks。

完整示例:SQL动态Pivot

DECLARE @DynamicPivotQuery AS NVARCHAR(MAX)
DECLARE @ColumnName AS NVARCHAR(MAX)

--Get distinct values of the PIVOT Column 
SELECT @ColumnName= ISNULL(@ColumnName + ',','') + QUOTENAME(Week)
FROM (SELECT DISTINCT Week FROM #StoreSales) AS Weeks

--Prepare the PIVOT query using the dynamic 
SET @DynamicPivotQuery = 
  N'SELECT Store, ' + @ColumnName + ' 
    FROM #StoreSales
    PIVOT(SUM(xCount) 
          FOR Week IN (' + @ColumnName + ')) AS PVTTable'
--Execute the Dynamic Pivot Query
EXEC sp_executesql @DynamicPivotQuery

以下是上面@Tayrn回答的修订版，可能会帮助你更容易理解旋转:

这可能不是最好的方法，但这帮助我理解了如何透视表。

ID =要主元的行数

MY_KEY =您要从原始表中选择的列，其中包含您想要进行主元转换的列名。

VAL =您希望在每列下返回的值。

MAX(VAL) =>可替换为其他聚合函数。Sum (val)， min (val)，等等…

DECLARE @cols AS NVARCHAR(MAX),
@query  AS NVARCHAR(MAX)
select @cols = STUFF((SELECT ',' + QUOTENAME(MY_KEY) 
                from yt
                group by MY_KEY
                order by MY_KEY ASC
        FOR XML PATH(''), TYPE
        ).value('.', 'NVARCHAR(MAX)') 
    ,1,1,'')
set @query = 'SELECT ID,' + @cols + ' from 
         (
            select ID, MY_KEY, VAL 
            from yt
        ) x
        pivot 
        (
            sum(VAL)
            for MY_KEY in (' + @cols + ')
        ) p '

        execute(@query);