SQL Server 中带有日期的 Pivot 和 UnPivot 功能答案

【问题标题】：Pivot & UnPivot functionality with dates in SQL ServerSQL Server 中带有日期的 Pivot 和 UnPivot 功能
【发布时间】：2017-09-12 19:10:09
【问题描述】：

我目前正在使用 pivot, unpivot 检索最后 6 个可用日期数据。谁能帮我解决这个问题？

select * 
from #myTable
unpivot (value for Area in (abc,def,fgh,ijk,klp)) up
pivot (max(value) for [date] in (
##-- Here I need to get the last 6 available dates less than current date
)) p

[Date] 列的数据类型为DATE.

我的数据库中的日期样本值

2017-09-16,
2017-09-09,
2017-09-02,
2017-08-26,
2017-07-22,
2017-07-01,
2017-06-24,
2017-06-11

Sample table, with expected result

【问题讨论】：

每个区域的最后 6 个或最后 6 个？样本数据和预期输出会很好。
是的每个区域...添加了示例表，预期结果也相同..提前致谢...

标签： sql sql-server tsql pivot unpivot

【解决方案1】：

嗯，根据您的示例数据，一个区域的前 6 个区域对于每个区域都是相同的，因为区域是列名。有了这些信息，我们可以在原始枢轴之后使用动态反枢轴。

declare @table table (TheDate date, abc int, def int, fgh int, ijk int, klp int)
insert into @table
values
('20170916',1,2,34,4,5),
('20170909',2,3,4,5,676),
('20170902',6,7,8,8,9)

DECLARE @DynamicPivotQuery AS NVARCHAR(MAX)
DECLARE @ColumnName AS NVARCHAR(MAX)

if object_id('tempdb..#staging') is not null drop table #staging

select
    Area
    ,TheDate
    ,Val
into #staging
from @table
unpivot 
    (Val for Area in (abc,def,fgh,ijk,klp)
    ) up


--Get distinct values of the PIVOT Column / top 6 by date
SELECT @ColumnName= ISNULL(@ColumnName + ',','') 
       + QUOTENAME(TheDate)
FROM (SELECT DISTINCT TOP 6 TheDate FROM #staging ORDER BY TheDate DESC) AS TheDate

--Prepare the PIVOT query using the dynamic 
SET @DynamicPivotQuery = 
  N'SELECT Area, ' + @ColumnName + '
    FROM #staging
    PIVOT(SUM(Val) 
          FOR TheDate IN (' + @ColumnName + ')) AS PVTTable'

--Execute the Dynamic Pivot Query
EXEC sp_executesql @DynamicPivotQuery

See It In Action Here

【讨论】：