在 SQL Server 中将表行展平为列 [重复]

Question

我有下面的 SQL 表，其中有随机生成的数据

  Code          Data
    SL Payroll    22
    SL Payroll    33
    SL Payroll    43
    ..            .....

我要传输数据，格式如下图

Code         Data1   Data2   Data3  ..
SL Payroll   22       33      43    ....  

有人建议使用数据透视表来转换数据，如下所示

SELECT Code,
       [22] Data1,
       [33] Data2,
       [43] Data3
FROM
    (
      SELECT *
      FROM T
    ) TBL
    PIVOT
    (
      MAX(Data) FOR Data IN([22],[33],[43])
    ) PVT

但这假设数据点是静态的，例如 22,33，但它们是动态生成的。

Answer 1

如果您知道或最大数量的所需列，您可以做一个简单的 PIVOT，否则，您需要 DYNAMIC

示例

 Select *
  From (
        Select [Code]
              ,[Data]
              ,[Col] = concat('Data',Row_Number() over (Partition By [Code] Order by 1/0))
         From  YourTable
       ) src
 Pivot (max([Data]) for [Col] in ([Data1],[Data2],[Data3],[Data4],[Data5])) pvt

退货

Code        Data1   Data2   Data3   Data4   Data5
SL Payroll  22      33      43      NULL    NULL

Answer 2

我会使用条件聚合和row_number():

select code,
       max(case when seqnum = 1 then code end) as code_1,
       max(case when seqnum = 2 then code end) as code_2,
       max(case when seqnum = 3 then code end) as code_3
from (select t.*,
             row_number() over (partition by code order by data) as seqnum
      from t
     ) t
group by code;

Answer 3

做动态支点我很久以前就做过了。

更新：更接近您的代码和传奇名称。

这适用于 PIVOT 所需的任意多列，不管是 1 还是 20

DECLARE @SelectFieldNameList as varchar(8000)
DECLARE @SelectFieldNameListCount as varchar(8000)
Set @SelectFieldNameList = ''
Set @SelectFieldNameListCount = ''

-- this section selects the list of firm location names and puts them in a string to be used in the pivot
-- it does it for the field select list and the count select using ISNULL so it puts a 0 if no counts returned
SELECT top (999999) @SelectFieldNameList = @SelectFieldNameList + case when @SelectFieldNameList = '' then '' else ', ' end 
+ '[' + Data + ']', 
@SelectFieldNameListCount = @SelectFieldNameListCount + case when @SelectFieldNameListCount = '' then '' else ', ' end 
+ 'ISNULL([' + Data + '], ''0'')' + Data 
From TableName
Where Data IS NOT NULL AND Ltrim(Data) <> ''
Group by Data

-- just for testing
select @SelectFieldNameList, @SelectFieldNameListCount


-- NOW USE THE ABOVE TO get the data pivoted with your dyanic fields
EXEC('
SELECT [Code], ' + @SelectFieldNameListCount + '
FROM (  
    SELECT [Code], Data, Sum(CountTotal) as CountTotal
    From TableName
    Group by [Code], Data
) AS TableToBePivoted
PIVOT (  
    SUM(CountTotal) 
    FOR Data IN (' + @SelectFieldNameList + ')  
) AS PivotedTable
order by [Code];  
')