间隔表中的间隔

Question

我有两个列的表,如下所示:

+-----------+------------+
|   FROM    |     TO     |
+-----------+------------+
|2015-03-01 | 2015-03-04 |
|2015-03-05 | 2015-03-09 |
+-----------+------------+

我想写一个函数,它将采用两个参数 - DateFrom和DateTo,并检查这个间隔.例如,如果函数接受DateFrom = 2015-03-03,并且DateTo = 2015-03-08作为参数应该返回true,因为此间隔中的每一天都在表中.

但如果表是这样的:

+-----------+------------+
|   FROM    |     TO     |
+-----------+------------+
|2015-03-01 | 2015-03-04 |
|2015-03-06 | 2015-03-09 |
+-----------+------------+

函数应该返回false,因为2015-03-05不在表中.算法的任何想法？谢谢你的帮助.

Answer 1

如果您还没有日历表,可以使用计数表:

DECLARE @t TABLE
    (
      FromDate DATE ,
      ToDate DATE
    )

INSERT  INTO @t
VALUES  ( '2015-03-01', '2015-03-04' ),
        ( '2015-03-05', '2015-03-09' )

DECLARE @from DATE =  '2015-03-03', @to DATE = '2015-03-08'

;WITH cte1 AS(SELECT ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) AS d
             FROM (VALUES(0),(0),(0),(0),(0),(0),(0),(0),(0),(0)) a(n)
             CROSS JOIN (VALUES(0),(0),(0),(0),(0),(0),(0),(0),(0),(0)) b(n)
             CROSS JOIN (VALUES(0),(0),(0),(0),(0),(0),(0),(0),(0),(0)) c(n)),
      cte2 AS(SELECT DATEADD(dd, d - 1, @from) AS d 
              FROM cte1 
              WHERE DATEADD(dd, d - 1, @from) <= @to)

SELECT  CASE WHEN EXISTS ( SELECT *
                           FROM cte2
                           WHERE NOT EXISTS ( SELECT *
                                              FROM   @t t
                                              WHERE  d BETWEEN t.FromDate AND t.ToDate ) )
             THEN 0
             ELSE 1
        END AS IntervalExists

它将适用于1000天差异的间隔.如果需要更多,只需添加更多cross joins(一个cross join将间隔乘以10).