如果您使用的日期范围尚未结束（仍在进行中），例如未设置endDate='0000-00-00'您不能使用BETWEEN，因为0000-00-00不是有效日期！

我使用了这个解决方案：

(Startdate BETWEEN '".$startdate2."' AND '".$enddate2."')  //overlap: starts between start2/end2
OR (Startdate < '".$startdate2."' 
  AND (enddate = '0000-00-00' OR enddate >= '".$startdate2."')
) //overlap: starts before start2 and enddate not set 0000-00-00 (still on going) or if enddate is set but higher then startdate2

如果startdate2高于enddate，则没有重叠！

@Bretana给出的数学解很好，但忽略了两个具体细节：

封闭或半开放间隔的方面空间隔

关于区间边界的封闭或开放状态，@Bretana的解对封闭区间有效

（起点A<=终点B）和（终点A>=起点B）

可以重写为半开间隔：

（开始A<结束B）和（结束A>开始B）

这种校正是必要的，因为根据定义，开放区间边界不属于区间的值范围。

关于空间隔，这里上面所示的关系不成立。根据定义不包含任何有效值的空间隔必须作为特殊情况处理。我通过Java时间库Time4J通过以下示例进行了演示：

MomentInterval a = MomentInterval.between(Instant.now(), Instant.now().plusSeconds(2));
MomentInterval b = a.collapse(); // make b an empty interval out of a

System.out.println(a); // [2017-04-10T05:28:11,909000000Z/2017-04-10T05:28:13,909000000Z)
System.out.println(b); // [2017-04-10T05:28:11,909000000Z/2017-04-10T05:28:11,909000000Z)

前导方括号“[”表示封闭的开始，而最后一个括号“）”表示开放的结束。

System.out.println(
      "startA < endB: " + a.getStartAsInstant().isBefore(b.getEndAsInstant())); // false
System.out.println(
      "endA > startB: " + a.getEndAsInstant().isAfter(b.getStartAsInstant())); // true

System.out.println("a overlaps b: " + a.intersects(b)); // a overlaps b: false

如上所示，空间隔违反了上面的重叠条件（尤其是startA<endB），因此Time4J（以及其他库）必须将其作为特殊的边缘情况来处理，以确保任何任意间隔与空间隔的重叠都不存在。当然，日期间隔（默认情况下在Time4J中是关闭的，但也可以是半开的，就像空日期间隔一样）的处理方式类似。

你可以试试这个：

//custom date for example
$d1 = new DateTime("2012-07-08");
$d2 = new DateTime("2012-07-11");
$d3 = new DateTime("2012-07-08");
$d4 = new DateTime("2012-07-15");

//create a date period object
$interval = new DateInterval('P1D');
$daterange = iterator_to_array(new DatePeriod($d1, $interval, $d2));
$daterange1 = iterator_to_array(new DatePeriod($d3, $interval, $d4));
array_map(function($v) use ($daterange1) { if(in_array($v, $daterange1)) print "Bingo!";}, $daterange);

在Microsoft SQL SERVER中-SQL函数

CREATE FUNCTION IsOverlapDates 
(
    @startDate1 as datetime,
    @endDate1 as datetime,
    @startDate2 as datetime,
    @endDate2 as datetime
)
RETURNS int
AS
BEGIN
DECLARE @Overlap as int
SET @Overlap = (SELECT CASE WHEN  (
        (@startDate1 BETWEEN @startDate2 AND @endDate2) -- caters for inner and end date outer
        OR
        (@endDate1 BETWEEN @startDate2 AND @endDate2) -- caters for inner and start date outer
        OR
        (@startDate2 BETWEEN @startDate1 AND @endDate1) -- only one needed for outer range where dates are inside.
        ) THEN 1 ELSE 0 END
    )
    RETURN @Overlap

END
GO

--Execution of the above code
DECLARE @startDate1 as datetime
DECLARE @endDate1 as datetime
DECLARE @startDate2 as datetime
DECLARE @endDate2 as datetime
DECLARE @Overlap as int
SET @startDate1 = '2014-06-01 01:00:00' 
SET @endDate1 =   '2014-06-01 02:00:00'
SET @startDate2 = '2014-06-01 01:00:00' 
SET @endDate2 =   '2014-06-01 01:30:00'

SET @Overlap = [dbo].[IsOverlapDates]  (@startDate1, @endDate1, @startDate2, @endDate2)

SELECT Overlap = @Overlap

这是我的Java解决方案，它也适用于无限区间

private Boolean overlap (Timestamp startA, Timestamp endA,
                         Timestamp startB, Timestamp endB)
{
    return (endB == null || startA == null || !startA.after(endB))
        && (endA == null || startB == null || !endA.before(startB));
}

这是一段神奇的代码：

 var isOverlapping =  ((A == null || D == null || A <= D) 
            && (C == null || B == null || C <= B)
            && (A == null || B == null || A <= B)
            && (C == null || D == null || C <= D));

哪里

A->1启动B->1结束C->2启动D->2结束

证据查看此测试控制台代码要点。