TSQL - 基于列值的动态列标题创建（Pivot / Unpivot）

Question

我必须处理以下表格结构，将其转换为类似下图中第二个表格的视图：

由于列＆＃34; Var_Columns ＆＃34;可以包含一百多个不同的值，我想要一些动态语句，它们将使用这些值来创建具有相应值的列标题。

理想情况下，月份名称的格式应为＆＃34; 2016-01-01＆＃34;一月等等。

我希望我能提供一些试用和错误代码，但我已经陷入了困境。 因此，我创建了一个SQL Fiddle，以便您查看。

希望有人知道如何解决这个问题。

谢谢，

丹尼尔

Answer 1

这是我的解决方案，使用动态sql来派生列名。

创建测试数据集：

CREATE TABLE input
    (
    [ID] int NOT NULL,
    [Version] [smallint] NOT NULL,
    [RowNo] [int] NOT NULL,
    [Dept] [nvarchar](max) NULL,
    [Info] [nvarchar](max) NULL,
    [Year] [nvarchar](max) NULL,
    [Var_Columns] [nvarchar](max) NULL,
    [January] [nvarchar](max) NULL,
    [Febuary] [nvarchar](max) NULL,
    [March] [nvarchar](max) NULL,
    [April] [nvarchar](max) NULL,
    [May] [nvarchar](max) NULL,
    [June] [nvarchar](max) NULL,
    [July] [nvarchar](max) NULL,
    [August] [nvarchar](max) NULL,
    [September] [nvarchar](max) NULL,
    [October] [nvarchar](max) NULL,
    [November] [nvarchar](max) NULL,
    [December] [nvarchar](max) NULL,
    )
;

INSERT INTO input
    ([ID], [Version], [RowNo],[Dept], [Info],[Year],[Var_Columns],[January],[Febuary], [March],[April],[May],[June],[July]
     ,[August],  [September] ,[October],[November],[December]
    )
VALUES
(1,2,1,'DeptA','Sheet','2016','varCol1','1','2','3','4','5','6','7','8','9','10','11','12'),
(1,2,2,'DeptA','Sheet','2016','varCol2','11','22','33','44','55','66','77','88','99','100','110','120'),
(1,2,3,'DeptA','Sheet','2016','varCol3','111','222','333','444','555','666','777','888','999','101','111','122'),
(2,2,1,'DeptB','Sheet','2016','varCol1','10','20','30','40','50','60','70','80','9','10','11','12')
;

实际解决方案：

--Create a variable to hold the column names for the unpivot
DECLARE @col VARCHAR(MAX)  = '';

-- insert the distinct Var_column entries into a temp table
IF OBJECT_ID('tempdb..#temp') IS NOT NULL
    DROP TABLE #temp; 
SELECT DISTINCT [Var_Columns] INTO #temp
FROM input

--Assign the distinct Var_column entries in the temp table to the variable @col
SELECT   @col +=  QUOTENAME([Var_Columns])+',' from #temp;

--generate the dynamic query
DECLARE @sql varchar(max) = ''

SELECT  @sql = '

;WITH CTE AS (
 SELECT * 
FROM 
   (SELECT [ID], [Version], [Dept], [Info],[Year],[Var_Columns],[January],[Febuary], [March],[April],[May],[June],[July],[August],[September],[October],[November],[December]
   FROM input) p
UNPIVOT
   ([Values] FOR [Month] IN 
      ([January],[Febuary], [March],[April],[May],[June],[July],[August],[September],[October],[November],[December])
)AS unpvt)

SELECT [ID], [Version], [Dept], [Info],[Year],[Month], 
'+SUBSTRING(@col,1,LEN(@col)-1)+'
FROM
(SELECT *
    FROM CTE) AS SourceTable
PIVOT
(
MAX([Values])
FOR Var_Columns IN ('+SUBSTRING(@col,1,LEN(@col)-1)+')
) AS PivotTable;

; '

-- prin the query and then execute.
print (@sql)
EXECUTE (@sql)

GO

结果：