Question

我有两个表，它们都有StartDate和EndDate列。

我正在尝试返回一个包含一个表（TableA）中所有日期范围的结果集，以及另一个表中的所有补充日期范围（TableB）。

CREATE TABLE [dbo].[TableA](
    [ID] [int] NOT NULL,
    [StartDate] [datetime] NOT NULL,
    [EndDate] [datetime] NOT NULL
)

CREATE TABLE [dbo].[TableB](
    [ID] [int] NOT NULL,
    [StartDate] [datetime] NOT NULL,
    [EndDate] [datetime] NOT NULL
)

INSERT INTO TableA (ID, StartDate, EndDate) VALUES(1, '4/1/2009', '8/1/2009')
INSERT INTO TableA (ID, StartDate, EndDate) VALUES(1, '10/1/2009', '12/1/2009')
INSERT INTO TableB (ID, StartDate, EndDate) VALUES(1, '1/1/2009', '2/1/2010')

INSERT INTO TableA (ID, StartDate, EndDate) VALUES(2, '4/1/2009', '8/1/2009')
INSERT INTO TableB (ID, StartDate, EndDate) VALUES(2, '1/1/2009', '5/1/2009')
INSERT INTO TableB (ID, StartDate, EndDate) VALUES(2, '7/1/2009', '12/1/2009')

三个数据集的预期结果集应为：

(ID = 1)
1/1/2009 - 4/1/2009 (from TableB)
4/1/2009 - 8/1/2009 (from TableA)
8/1/2009 - 10/1/2009 (from TableB)
10/1/2009 - 12/1/2009 (from TableA)
12/1/2009 - 2/1/2010 (from TableB)

(ID = 2)
1/1/2009 - 4/1/2009 (from TableB)
4/1/2009 - 8/1/2009 (from TableA)
8/1/2009 - 12/1/2009 (from TableB)

日期范围不保证是连续的，我不能对它们在表格之间的重叠方式做出任何假设......在每个表格中，它们可以假设不重叠。

我在解决如何将TableB中的单个日期范围拆分成多个部分以查找SQL中的所有补充“区域”时遇到了问题。

有人有任何建议吗？

Answer 1

如果您将其创建为视图，我认为它可以满足您的需求。它使用CTE，它应该由SQL Server 2005支持，但不能更早。

WITH Timestamps AS (
    SELECT Id, StartDate AS Date FROM TableA
    UNION
    SELECT Id, EndDate AS Date FROM TableA
    UNION
    SELECT Id, StartDate AS Date FROM TableB
    UNION
    SELECT Id, EndDate AS Date FROM TableB
), Timestamps2 AS (
    SELECT ROW_NUMBER() OVER (ORDER BY Id, Date) AS RowNumber, * FROM Timestamps
), Timestamps3 AS (
    SELECT T1.ID, T1.Date AS StartDate, T2.Date AS EndDate
    FROM Timestamps2 AS T1 JOIN Timestamps2 AS T2
    ON T1.RowNumber + 1 = T2.RowNumber AND T1.ID = T2.ID
), IntervalsFromB AS (
    SELECT T.ID, T.StartDate, T.EndDate FROM Timestamps3 AS T
    LEFT JOIN TableA AS A
    ON T.StartDate >= A.StartDate AND T.EndDate <= A.EndDate
    WHERE A.StartDate IS NULL)
SELECT * FROM TableA
UNION ALL
SELECT * FROM IntervalsFromB

完整输出（按Id，StartDate排序以便于阅读）：

Id  StartDate               EndDate
1   2009-01-01 00:00:00.000 2009-04-01 00:00:00.000
1   2009-04-01 00:00:00.000 2009-08-01 00:00:00.000
1   2009-08-01 00:00:00.000 2009-10-01 00:00:00.000
1   2009-10-01 00:00:00.000 2009-12-01 00:00:00.000
1   2009-12-01 00:00:00.000 2010-02-01 00:00:00.000
2   2009-01-01 00:00:00.000 2009-04-01 00:00:00.000
2   2009-04-01 00:00:00.000 2009-08-01 00:00:00.000
2   2009-08-01 00:00:00.000 2009-12-01 00:00:00.000

实现这一点对我来说非常复杂，所以我想知道是否有人能看到更简单的方法。我可能会错过一些让这更简单的技巧。如果是这样，请告诉我！此外，如果您有很多行，您几乎肯定需要在表上使用某些索引才能使其表现良好。其他一些优化也许是可能的 - 我没有尝试过尽可能快的性能，只是为了得到正确的结果。

查找补充日期范围？

1 个答案: