PIVOT 动态地将行旋转到列中

Question

我在每一行都有一张客户表及其购买类型和购买说明。

我想调整购买类型和备注，以便每一行只代表一个客户实例。

表格：

Customer ID  | Name | Purchase Type | Purchase Notes
-------------+------+---------------+---------------
1            | John | Furniture     | TextABC 
1            | John | Appliance     | TextDEF 
1            | John | Accessory     | TextGHI 

目标：

Customer ID  | Name | Purchase Type 1 | Purchase Notes 1 | Purchase Type 2| Purchase Notes 2  | Purchase Type 3 | Purchase Notes 3
------------ +------+-----------------+------------------+----------------+-------------------+-----------------+------------------
1            | John | Furniture       |TextABC           | Appliance      | TextDEF           | Accessory       | TextGHI

要求：

我无法对任何购买类型或备注进行硬编码，因为它们可以更改。 我无法确定有多少种类型，因为它可能是 9 种或 4 种，具体取决于客户。

如何将编号添加到标题中，以便表格最多可以包含 x，但那些小于 x 的客户只会有空白？

阅读有关 SQL Pivot 的论坛，我似乎无法找到一种方法来做到这一点，而无需对其进行硬编码。

Answer 1

你可以使用动态TSQL和PIVOT:

if OBJECT_ID('dbo.test') is null 
    create table dbo.test (CustomerID int , [Name] varchar(50), PurchaseType varchar(50), PurchaseNotes varchar(50))
truncate table dbo.test 

--populate test table
insert into dbo.test values
 (1, 'John','Furniture','TextABC'), (1, 'John','Appliance','TextDEF'), (1, 'John','Accessory','TextGHI')
,(2, 'Mary','Furniture','TextJKL'), (2, 'Mary','Appliance','TextMNO'), (2, 'Mary','Accessory','TextPQR'), (2, 'Mary','New type','TextSTU') 

declare @total         int
declare @counter       int = 1
declare @PurchaseNotes nvarchar(max)='' --holds all the PurchaseNotes column names 
declare @PurchaseType  nvarchar(max)='' --holds all the PurchaseType column names  
declare @Combo         nvarchar(max)='' --holds the combination of PurchaseType and PurchaseNotes for the final SELECT statement
declare @sql           nvarchar(max)='' --contains the TSQL dinamically generated 

--count distinct Purchase Types
select @total = count(distinct [PurchaseType]) from dbo.test 

--build headers
while @counter <= @total
    begin
       set @PurchaseNotes = @PurchaseNotes + ' [PurchaseNotes' + cast(@counter as varchar(max)) + '],'
       set @PurchaseType = @PurchaseType + ' [PurchaseType' + cast(@counter as varchar(max)) + '],'
       set @Combo = @Combo + ' [PurchaseType' + cast(@counter as varchar(max)) + '],'+ ' [PurchaseNotes' + cast(@counter as varchar(max)) + '],'
       set @counter = @counter + 1
    end

set @PurchaseNotes = left(@PurchaseNotes,len(@PurchaseNotes)-1) + ' '
set @PurchaseType = left(@PurchaseType,len(@PurchaseType)-1)+ ' '
set @Combo = left(@Combo,len(@Combo)-1)+ ' '

--create dynamic TSQL query
set @sql = @sql + ' SELECT T.CustomerID, T.[Name],' + @Combo
set @sql = @sql + ' FROM '
set @sql = @sql + ' ( '
set @sql = @sql + '     SELECT [CustomerID],[Name],[PurchaseType],'
set @sql = @sql + '         CONCAT(''PurchaseType'',ROW_NUMBER() OVER (PARTITION BY customerid ORDER BY customerid, [Name])) AS COL  '
set @sql = @sql + '     FROM  dbo.test '
set @sql = @sql + ' ) SRC '
set @sql = @sql + ' PIVOT '
set @sql = @sql + ' ( '
set @sql = @sql + '     MAX(PurchaseType) '
set @sql = @sql + '     FOR COL IN (' + @PurchaseType + ') '
set @sql = @sql + ' ) AS T '
set @sql = @sql + ' inner join '
set @sql = @sql + ' ('
set @sql = @sql + '     SELECT * '
set @sql = @sql + '     FROM '
set @sql = @sql + '     ( '
set @sql = @sql + '         SELECT [CustomerID],[Name],[PurchaseNotes],'
set @sql = @sql + '             CONCAT(''PurchaseNotes'',ROW_NUMBER() OVER (PARTITION BY customerid ORDER BY customerid, [Name])) AS COL2 '
set @sql = @sql + '         FROM  dbo.test '
set @sql = @sql + '     ) SRC '
set @sql = @sql + '      PIVOT '
set @sql = @sql + '     ( '
set @sql = @sql + '         MAX(PurchaseNotes) '
set @sql = @sql + '         FOR COL2 IN (' + @PurchaseNotes + ') '
set @sql = @sql + '     ) AS PVT2 '
set @sql = @sql + ' ) N'
set @sql = @sql + '  on T.CustomerID = N.CustomerID'

--execute dynamic query
exec (@sql)

输入（我用新的 PurchaseType 添加了另一个客户）：

结果：