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我在 SQL Server 2008/2012 上。我有一个计数表#MonthTally

;WITH
  Pass0 AS (SELECT 1 AS C UNION all SELECT 1), --2 rows
  Pass1 AS (SELECT 1 AS C FROM Pass0 AS A, Pass0 AS B),--4 rows
  Pass2 AS (SELECT 1 AS C FROM Pass1 AS A, Pass1 AS B),--16 rows
  Pass3 AS (SELECT 1 AS C FROM Pass2 AS A, Pass2 AS B),--256 rows
  Tally AS (SELECT ROW_NUMBER() OVER(ORDER BY C) AS N FROM Pass3)
SELECT TOP 256 ROW_NUMBER() OVER (ORDER BY (SELECT 0)) AS N
INTO #MonthTally
FROM Tally
ORDER BY N

我正在使用这样的计数表

-- Insert 5 future years
SELECT TOP(5) V.CompanyId, V.StartDate, V.EndDate
FROM #MonthTally T
CROSS APPLY
(   
SELECT
    F.CompanyId,
    DATEADD(YY, T.N,MAX(F.StartDate)) AS StartDate,
    DATEADD(YY, T.N,MAX(F.EndDate)) AS EndDate
    FROM FiscalPeriods F
    GROUP BY CompanyId  
) V

我已经读过，每当您使用 TOP 时，您应该始终使用 ORDER BY 来确保 TOP 返回什么。所以我不能指望SELECT TOP(5) * FROM #MonthTally总是返回 1 到 5，除非我使用 ORDER BY，不管数据是如何插入到#MonthTally. 但是如何在我的 CROSS APPLY 上获得 ORDER BY。

它不会更糟，然后我可以在 CROSS APPLY 之外进行聚合。无论如何，它对每条线的 GROUP BY 可能表现不佳。但无论如何我都想知道。

4

1 回答 1

0

在这种情况下，我只会使用WHERE N BETWEEN 1 AND 5.

一般来说，尽管您可以将查询放入使用的 CTE 或子查询中TOP

WITH T AS
(
SELECT TOP(5) N
FROM #MonthTally
ORDER BY N
)
SELECT V.CompanyId, V.StartDate, V.EndDate
FROM T
CROSS APPLY
(   
SELECT
    F.CompanyId,
    DATEADD(YY, T.N,MAX(F.StartDate)) AS StartDate,
    DATEADD(YY, T.N,MAX(F.EndDate)) AS EndDate
    FROM FiscalPeriods F
    GROUP BY CompanyId  
) V
ORDER BY T.N
于 2013-05-29T09:13:18.303 回答