我的任务是想出一种翻译以下数据的方法:

date        category        amount
1/1/2012    ABC             1000.00
2/1/2012    DEF             500.00
2/1/2012    GHI             800.00
2/10/2012   DEF             700.00
3/1/2012    ABC             1100.00

分为以下几种:

date        ABC             DEF             GHI
1/1/2012    1000.00
2/1/2012                    500.00
2/1/2012                                    800.00
2/10/2012                   700.00
3/1/2012    1100.00

空白点可以是null,也可以是空白,任何一种都可以,类别需要是动态的。另一个可能的警告是,我们将以有限的容量运行查询,这意味着临时表将无法使用。我尝试过研究,并且已经登陆了PIVOT,但因为我以前从未使用过它,所以我真的不理解它,尽管我尽了最大的努力去弄清楚它。有人能告诉我正确的方向吗?


当前回答

完全通用的方式,将在非传统的MS SQL环境中工作(例如Azure Synapse Analytics无服务器SQL池)-它在SPROC中,但不需要这样使用…

-- DROP PROCEDURE IF EXISTS
if object_id('dbo.usp_generic_pivot') is not null 
     DROP PROCEDURE dbo.usp_generic_pivot
GO;

CREATE PROCEDURE dbo.usp_generic_pivot (
    @source NVARCHAR (100), -- table or view object name
   @pivotCol NVARCHAR (100), -- the column to pivot
   @pivotAggCol NVARCHAR (100), -- the column with the values for the pivot
   @pivotAggFunc NVARCHAR (20), -- the aggregate function to apply to those values
   @leadCols NVARCHAR (100) -- comma seprated list of other columns to keep and order by
)
AS
BEGIN
   DECLARE @pivotedColumns NVARCHAR(MAX)
   DECLARE @tsql NVARCHAR(MAX)

   SET @tsql = CONCAT('SELECT @pivotedColumns = STRING_AGG(qname, '','') FROM (SELECT DISTINCT QUOTENAME(', @pivotCol,') AS qname FROM ',@source, ') AS qnames')
   EXEC sp_executesql @tsql, N'@pivotedColumns nvarchar(max) out', @pivotedColumns out

   SET @tsql = CONCAT ( 'SELECT ', @leadCols,   ',', @pivotedColumns,' FROM ',' ( SELECT ',@leadCols,',',
         @pivotAggCol,',',   @pivotCol,   ' FROM ',   @source,   ') as t ',
         ' PIVOT (', @pivotAggFunc,   '(', @pivotAggCol,   ')',' FOR ',   @pivotCol,
         '   IN (', @pivotedColumns,')) as pvt ',' ORDER BY ',   @leadCols)

   EXEC (@tsql)

END
GO;

-- TEST EXAMPLE
EXEC dbo.usp_generic_pivot  
    @source  = '[your_db].[dbo].[form_answers]',
   @pivotCol  = 'question', 
   @pivotAggCol   = 'answer',
   @pivotAggFunc  = 'MAX', 
   @leadCols    = 'candidate_id, candidate_name' 
GO;

其他回答

我知道这个问题已经很老了,但我正在看答案,并认为我可能能够扩展问题的“动态”部分,并可能帮助别人。

首先,我构建这个解决方案是为了解决几个同事遇到的需要快速旋转的不恒定和大型数据集的问题。

这个解决方案需要创建一个存储过程,所以如果这对您的需求来说是不可能的,请停止阅读。

This procedure is going to take in the key variables of a pivot statement to dynamically create pivot statements for varying tables, column names and aggregates. The Static column is used as the group by / identity column for the pivot(this can be stripped out of the code if not necessary but is pretty common in pivot statements and was necessary to solve the original issue), the pivot column is where the end resultant column names will be generated from, and the value column is what the aggregate will be applied to. The Table parameter is the name of the table including the schema (schema.tablename) this portion of the code could use some love because it is not as clean as I would like it to be. It worked for me because my usage was not publicly facing and sql injection was not a concern. The Aggregate parameter will accept any standard sql aggregate 'AVG', 'SUM', 'MAX' etc. The code also defaults to MAX as an aggregate this is not necessary but the audience this was originally built for did not understand pivots and were typically using max as an aggregate.

让我们从创建存储过程的代码开始。这段代码应该可以在SSMS 2005及以上的所有版本中工作,但我没有在2005年或2016年测试它,但我不明白为什么它不能工作。

create PROCEDURE [dbo].[USP_DYNAMIC_PIVOT]
    (
        @STATIC_COLUMN VARCHAR(255),
        @PIVOT_COLUMN VARCHAR(255),
        @VALUE_COLUMN VARCHAR(255),
        @TABLE VARCHAR(255),
        @AGGREGATE VARCHAR(20) = null
    )

AS


BEGIN

SET NOCOUNT ON;
declare @AVAIABLE_TO_PIVOT NVARCHAR(MAX),
        @SQLSTRING NVARCHAR(MAX),
        @PIVOT_SQL_STRING NVARCHAR(MAX),
        @TEMPVARCOLUMNS NVARCHAR(MAX),
        @TABLESQL NVARCHAR(MAX)

if isnull(@AGGREGATE,'') = '' 
    begin
        SET @AGGREGATE = 'MAX'
    end


 SET @PIVOT_SQL_STRING =    'SELECT top 1 STUFF((SELECT distinct '', '' + CAST(''[''+CONVERT(VARCHAR,'+ @PIVOT_COLUMN+')+'']''  AS VARCHAR(50)) [text()]
                            FROM '+@TABLE+'
                            WHERE ISNULL('+@PIVOT_COLUMN+','''') <> ''''
                            FOR XML PATH(''''), TYPE)
                            .value(''.'',''NVARCHAR(MAX)''),1,2,'' '') as PIVOT_VALUES
                            from '+@TABLE+' ma
                            ORDER BY ' + @PIVOT_COLUMN + ''

declare @TAB AS TABLE(COL NVARCHAR(MAX) )

INSERT INTO @TAB EXEC SP_EXECUTESQL  @PIVOT_SQL_STRING, @AVAIABLE_TO_PIVOT 

SET @AVAIABLE_TO_PIVOT = (SELECT * FROM @TAB)


SET @TEMPVARCOLUMNS = (SELECT replace(@AVAIABLE_TO_PIVOT,',',' nvarchar(255) null,') + ' nvarchar(255) null')


SET @SQLSTRING = 'DECLARE @RETURN_TABLE TABLE ('+@STATIC_COLUMN+' NVARCHAR(255) NULL,'+@TEMPVARCOLUMNS+')  
                    INSERT INTO @RETURN_TABLE('+@STATIC_COLUMN+','+@AVAIABLE_TO_PIVOT+')

                    select * from (
                    SELECT ' + @STATIC_COLUMN + ' , ' + @PIVOT_COLUMN + ', ' + @VALUE_COLUMN + ' FROM '+@TABLE+' ) a

                    PIVOT
                    (
                    '+@AGGREGATE+'('+@VALUE_COLUMN+')
                    FOR '+@PIVOT_COLUMN+' IN ('+@AVAIABLE_TO_PIVOT+')
                    ) piv

                    SELECT * FROM @RETURN_TABLE'



EXEC SP_EXECUTESQL @SQLSTRING

END

接下来,我们将为示例准备数据。我从公认的答案中选取了数据示例,并添加了两个数据元素,用于这个概念证明,以显示聚合更改的各种输出。

create table temp
(
    date datetime,
    category varchar(3),
    amount money
)

insert into temp values ('1/1/2012', 'ABC', 1000.00)
insert into temp values ('1/1/2012', 'ABC', 2000.00) -- added
insert into temp values ('2/1/2012', 'DEF', 500.00)
insert into temp values ('2/1/2012', 'DEF', 1500.00) -- added
insert into temp values ('2/1/2012', 'GHI', 800.00)
insert into temp values ('2/10/2012', 'DEF', 700.00)
insert into temp values ('2/10/2012', 'DEF', 800.00) -- addded
insert into temp values ('3/1/2012', 'ABC', 1100.00)

下面的示例作为一个简单的示例,展示了显示不同聚合的不同执行语句。为了保持示例的简单性,我没有选择更改静态列、主列和值列。您应该能够复制和粘贴代码,自己开始处理它

exec [dbo].[USP_DYNAMIC_PIVOT] 'date','category','amount','dbo.temp','sum'
exec [dbo].[USP_DYNAMIC_PIVOT] 'date','category','amount','dbo.temp','max'
exec [dbo].[USP_DYNAMIC_PIVOT] 'date','category','amount','dbo.temp','avg'
exec [dbo].[USP_DYNAMIC_PIVOT] 'date','category','amount','dbo.temp','min'

此执行将分别返回以下数据集。

动态SQL PIVOT:

create table temp
(
    date datetime,
    category varchar(3),
    amount money
)

insert into temp values ('1/1/2012', 'ABC', 1000.00)
insert into temp values ('2/1/2012', 'DEF', 500.00)
insert into temp values ('2/1/2012', 'GHI', 800.00)
insert into temp values ('2/10/2012', 'DEF', 700.00)
insert into temp values ('3/1/2012', 'ABC', 1100.00)


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

SET @cols = STUFF((SELECT distinct ',' + QUOTENAME(c.category) 
            FROM temp c
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')
    
set @query = 'SELECT date, ' + @cols + ' from 
            (
                select date
                    , amount
                    , category
                from temp
           ) x
            pivot 
            (
                 max(amount)
                for category in (' + @cols + ')
            ) p '


execute(@query)

drop table temp

结果:

Date                        ABC         DEF    GHI
2012-01-01 00:00:00.000     1000.00     NULL    NULL
2012-02-01 00:00:00.000     NULL        500.00  800.00
2012-02-10 00:00:00.000     NULL        700.00  NULL
2012-03-01 00:00:00.000     1100.00     NULL    NULL

SQL Server 2017的更新版本使用STRING_AGG函数来构造主列列表:

create table temp
(
    date datetime,
    category varchar(3),
    amount money
);

insert into temp values ('20120101', 'ABC', 1000.00);
insert into temp values ('20120201', 'DEF', 500.00);
insert into temp values ('20120201', 'GHI', 800.00);
insert into temp values ('20120210', 'DEF', 700.00);
insert into temp values ('20120301', 'ABC', 1100.00);


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

SET @cols = (SELECT STRING_AGG(category,',') FROM (SELECT DISTINCT category FROM temp WHERE category IS NOT NULL)t);

set @query = 'SELECT date, ' + @cols + ' from 
            (
                select date
                    , amount
                    , category
                from temp
           ) x
            pivot 
            (
                 max(amount)
                for category in (' + @cols + ')
            ) p ';

execute(@query);

drop table temp;
CREATE TABLE #PivotExample(
   [ID]      [nvarchar](50)   NULL,       
   [Description]   [nvarchar](50)   NULL,
   [ClientId]   [smallint] NOT NULL,
)
GO


INSERT   #PivotExample  ([ID],[Description],   [ClientId])   VALUES ('ACI1','ACI1Desc1',1008)
INSERT   #PivotExample  ([ID],[Description],   [ClientId])   VALUES ('ACI1','ACI1Desc2',2000)
INSERT   #PivotExample  ([ID],[Description],   [ClientId])   VALUES ('ACI1','ACI1Desc3',3000)
INSERT   #PivotExample  ([ID],[Description],   [ClientId])   VALUES ('ACI1','ACI1Desc4',4000)
INSERT   #PivotExample  ([ID],[Description],   [ClientId])   VALUES ('ACI2','ACI2Desc1',5000)
INSERT   #PivotExample  ([ID],[Description],   [ClientId])   VALUES ('ACI2','ACI2Desc2',6000)
INSERT   #PivotExample  ([ID],[Description],   [ClientId])   VALUES ('ACI2','ACI2Desc3', 7000)

SELECT * FROM #PivotExample




--Declare necessary variables
DECLARE   @SQLQuery AS NVARCHAR(MAX)
DECLARE   @PivotColumns AS NVARCHAR(MAX)
 
--Get unique values of pivot column  
SELECT   @PivotColumns= COALESCE(@PivotColumns + ',','') + QUOTENAME([Description])
FROM (SELECT DISTINCT [Description] FROM [dbo].#PivotExample) AS PivotExample
 
--SELECT   @PivotColumns
 
--Create the dynamic query with all the values for 
--pivot column at runtime
SET   @SQLQuery = 
    N' -- Your pivoted result comes here
    SELECT ID, ' + @PivotColumns + '
    FROM 
    (
        -- Source table should in a inner query
        SELECT ID,[Description],[ClientId]
        FROM #PivotExample
    )AS P
    PIVOT
    (     
          -- Select the values from derived table P
          SUM(ClientId) 
          FOR [Description] IN (' + @PivotColumns + ') 
    )AS PVTTable'
 
--SELECT   @SQLQuery
--Execute dynamic query
EXEC sp_executesql @SQLQuery


Drop table #PivotExample

Taryn的答案的一个版本的性能改进:

Data

CREATE TABLE dbo.Temp
(
    [date] datetime NOT NULL,
    category nchar(3) NOT NULL,
    amount money NOT NULL,

    INDEX [CX dbo.Temp date] CLUSTERED ([date]),
    INDEX [IX dbo.Temp category] NONCLUSTERED (category)
);

INSERT dbo.Temp
    ([date], category, amount)
VALUES
    ({D '2012-01-01'}, N'ABC', $1000.00),
    ({D '2012-01-02'}, N'DEF', $500.00),
    ({D '2012-01-02'}, N'GHI', $800.00),
    ({D '2012-02-10'}, N'DEF', $700.00),
    ({D '2012-03-01'}, N'ABC', $1100.00);

动态主

DECLARE 
    @Delimiter nvarchar(4000) = N',',
    @DelimiterLength bigint,
    @Columns nvarchar(max),
    @Query nvarchar(max);

SET @DelimiterLength = LEN(REPLACE(@Delimiter, SPACE(1), N'#'));

-- Before SQL Server 2017
SET @Columns =
    STUFF
    (
        (
            SELECT 
                [text()] = @Delimiter,
                [text()] = QUOTENAME(T.category)
            FROM dbo.Temp AS T
            WHERE T.category IS NOT NULL
            GROUP BY T.category
            ORDER BY T.category
            FOR XML PATH (''), TYPE
        )
        .value(N'text()[1]', N'nvarchar(max)'),
        1, @DelimiterLength, SPACE(0)
    );

-- Alternative for SQL Server 2017+ and database compatibility level 110+
SELECT @Columns = 
    STRING_AGG(CONVERT(nvarchar(max), QUOTENAME(T.category)), N',')
        WITHIN GROUP (ORDER BY T.category)
FROM 
(
    SELECT T2.category
    FROM dbo.Temp AS T2
    WHERE T2.category IS NOT NULL
    GROUP BY T2.category
) AS T;

IF @Columns IS NOT NULL
BEGIN
    SET @Query = 
        N'SELECT [date], ' + 
        @Columns + 
        N' 
        FROM
        (
            SELECT [date], amount, category
            FROM dbo.Temp
        ) AS S
        PIVOT
        (
            MAX(amount)
            FOR category IN (' +
            @Columns +
            N')
        ) AS P;';

    EXECUTE sys.sp_executesql @Query;
END;

执行计划

结果

date ABC DEF GHI
2012-01-01 00:00:00.000 1000.00 NULL NULL
2012-01-02 00:00:00.000 NULL 500.00 800.00
2012-02-10 00:00:00.000 NULL 700.00 NULL
2012-03-01 00:00:00.000 1100.00 NULL NULL