Question

我有一张包含以下数据的表格：

Fiscal Year | Fiscal Quarter | Fiscal Week | Data
2009        | 2              | 22          | 9.5
2009        | 2              | 24          | 8.8
2009        | 2              | 26          | 8.8
2009        | 3              | 28          | 8.8
2009        | 3              | 31          | 9.1
2009        | 3              | 33          | 8.8

我想写一个产生以下内容的查询：

Fiscal Year | Fiscal Quarter | Fiscal Week | Data | Trend
2009        | 2              | 22          | 9.5  | NULL
2009        | 2              | 24          | 8.8  | -0.7
2009        | 2              | 26          | 8.8  | 0
2009        | 3              | 28          | 8.8  | 0
2009        | 3              | 31          | 9.1  | 0.3
2009        | 3              | 33          | 8.8  | -0.3

我知道这可以通过将表与上一个会计周简单地连接到自身来轻松实现，但这并不总是简单的t1.[Fiscal Week] = t2.[Fiscal Week] - 2，因为有时差异是3周。

我可以通过以下方式轻松获取最大记录：

SELECT
    MAX(t1.[Fiscal Week]) "LastWeek"
FROM t1
WHERE t1.[Fiscal Year] = 2009
    AND t1.[Fiscal Week] < 31

但是，当涉及抽象它以使加入工作时，我感到很茫然。

如何在“比当前记录小的最大财政周”中进行自我加入？

Answer 1

使用Sql 2005+执行此操作的最简单方法是使用ranking and windowing functions - 只需对数据进行分区/排序，并为每条记录分配一个合适的序列（在这种情况下，您将按财务年度进行分区，并按财务周期进行排序）那个窗口） - 看起来像这样：

with data as
(
    select  row_number() over (partition by a.fiscalYear order by a.fiscalWeek) as rn,
            a.fiscalYear, a.fiscalQuarter, a.fiscalWeek, a.Data
    from    #TableName a
)
select  a.fiscalYear, a.fiscalQuarter, a.fiscalWeek, a.Data, 
        a.Data - b.Data as Trend
from    data a
left join data b
on      a.fiscalYear = b.fiscalYear
and     a.rn = b.rn + 1
order by a.fiscalYear, a.rn

这个特定的查询不允许在financialYear边界上进行扩展 - 如果你想扩展到跨越这些年份的边界，你只需要删除“partition by”子句和“fiscalYear”连接条件，而是通过组合来排序集合财政年度和财政周刊，如下：

with data as
(
    select  row_number() over (order by a.fiscalYear + a.fiscalWeek) as rn,
            a.fiscalYear, a.fiscalQuarter, a.fiscalWeek, a.Data
    from    #TableName a
)
select  a.fiscalYear, a.fiscalQuarter, a.fiscalWeek, a.Data, 
        a.Data - b.Data as Trend
from    data a
left join data b
on      a.rn = b.rn + 1
order by a.rn

Answer 2

如果您使用的是SQL Server 2005，则可以使用CROSS APPLY子句。

这里你可以有一个表值函数，它将返回财政周的行，在当前行的那一行之前。

CREATE FUNCTION dbo.fn_GetFiscalWeekBeforeThis(@Year AS int, 
  @CurrentWeek as int)
  RETURNS TABLE
AS
RETURN
  SELECT TOP 1 *
  FROM t1
  WHERE [Fiscal Year] = @Year 
  AND [Fiscal Week] < @CurrentWeek
  ORDER BY [Fiscal Week] DESC
GO

然后，

SELECT A.*,
A.Data - B.Data
FROM
t1 A
CROSS APPLY 
   dbo.fn_GetFiscalWeekBeforeThis(A.[Fiscal Year],  
   A.[Fiscal Week]) AS B

编辑：请注意，我通过查看文章＆amp;修改了SQL。没有IDE 另外，我不知道 - 它如何适用于第一行。

所以，请善待：）

EDIT2：让我知道，如果它根本不起作用。
这将有助于我知道 - 不回答问题而不检查结果。

EDIT3：我已经从函数中删除了对Quarter参数的需求。

Answer 3

这有用吗？内联查询有点令人满意，并且可能有更好的方法...

select
  [fiscal year]
, [fiscal quarter]
, [fiscal week]
, [data] 
, (
    select top 1 (i.data - t1.data) from t1 as i
    where i.[fiscal year] >= t1.[fiscal year]
    and i.[fiscal quarter] >= t1.[fiscal quarter]
    and i.[fiscal week] >= t1.[fiscal week]
    and (
          i.[fiscal year] <> t1.[fiscal year]
       or i.[fiscal quarter] <> t1.[fiscal quarter]
       or i.[fiscal week] <> t1.[fiscal week]
    )
    order by [fiscal year] asc, [fiscal quarter] asc, [fiscal week] asc
) as trend
from t1

Answer 4

DECLARE @Fiscal TABLE
  ( 
   FiscalYear int
  ,FiscalQuarter int
  ,FiscalWeek int
  ,[Data] decimal(4,1) 
  )

INSERT INTO @Fiscal
          ( FiscalYear, FiscalQuarter, FiscalWeek, [Data] )
SELECT 2009, 2, 22, 9.5 UNION
SELECT 2009, 2, 24, 8.8 UNION
SELECT 2009, 2, 26, 8.8 UNION
SELECT 2009, 3, 28, 8.8 UNION
SELECT 2009, 3, 31, 9.1 UNION
SELECT 2009, 3, 33, 8.8 UNION
SELECT 2010, 1, 1, 9.0 UNION
SELECT 2010, 1, 2, 9.2

;
WITH  abcd
        AS ( SELECT FiscalYear
                   ,FiscalQuarter
                   ,FiscalWeek
                   ,[Data]
                   ,row_number() OVER ( ORDER BY FiscalYear, FiscalWeek ) AS rn
             FROM   @Fiscal
           )
  SELECT  a.FiscalYear
         ,a.FiscalQuarter
         ,a.FiscalWeek
         ,a.[Data]
         ,a.[Data] - b.[Data] AS [Trend]
  FROM    abcd AS a
          LEFT JOIN abcd AS b ON b.rn = ( a.rn - 1 )
  ORDER BY a.FiscalYear
         ,a.FiscalWeek

自我加入可变数据

4 个答案: