日期范围内的 SQL PIVOT

Question

我正在尝试转换此日期列表以用作列标题。示例查询已针对 12 个日历月进行了简化注意：实际日期范围最终将总共为 240 个月。我对 PIVOT 功能不太了解

DROP TABLE if exists #nbrs
DROP TABLE if exists #nbr

DECLARE @StartDate DATE = '20210101'
DECLARE @EndDate DATE = '20211201'

SELECT  DATEADD(MONTH, nbr - 1, @StartDate) AS DateRange
    FROM    ( SELECT    ROW_NUMBER() OVER ( ORDER BY c.object_id ) AS Nbr
          FROM      sys.columns c
        ) nbrs 
WHERE   nbr - 1 <= DATEDIFF(MONTH, @StartDate, @EndDate) 

当前输出：

DateRange
2021-01-01
2021-02-01
2021-03-01
2021-04-01
2021-05-01
2021-06-01
2021-07-01
2021-08-01
2021-09-01
2021-10-01
2021-11-01
2021-12-01

期望的输出：

2021-01-01	2021-02-01	2021-03-01

Answer 1

您可以通过使用动态 sql 查询和数据透视函数来实现所需的输出。除了日期列之外，我还为枢轴函数添加了另一个虚拟列。

DECLARE @StartDate DATE = '20210101';
DECLARE @EndDate DATE = '20211201';
DECLARE @DynamicQuery AS NVARCHAR(MAX);
DECLARE @ColumnList AS NVARCHAR(MAX);

-- populate column list 
WITH DateRange(DateData) AS 
(
    SELECT @StartDate as Date
    UNION ALL
    SELECT DATEADD(MONTH,1,DateData)
    FROM DateRange 
    WHERE DateData < @EndDate
)
SELECT @ColumnList = ISNULL(@ColumnList + ',', '')
        + QUOTENAME(DateData)
FROM DateRange
OPTION (MAXRECURSION 300);

-- Construct dynamic query
SELECT @DynamicQuery = N' WITH DateRange(DateData, AnotherColumn) AS 
      (
          SELECT CAST(''' + CAST(@StartDate AS NVARCHAR) + ''' as Date) as DateData, 1 as AnotherColumn
          UNION ALL
          SELECT DATEADD(MONTH,1,DateData), 1 as AnotherColumn
          FROM DateRange 
          WHERE DateData <  ''' + CAST(@EndDate  AS NVARCHAR) + '''
      )
      SELECT ' + @ColumnList + ' FROM (
      SELECT * FROM DateRange
    ) As SouceTable PIVOT (MAX(AnotherColumn) FOR DateData IN ( ' +
    @ColumnList + ')) AS PivotTable
    OPTION (MAXRECURSION 300)';

-- run @DynamicQuery;
EXEC sp_executesql @DynamicQuery;

结果：