给定两个日期范围,确定两个日期是否重叠的最简单或最有效的方法是什么?
例如,假设我们有由DateTime变量StartDate1到EndDate1和StartDate2到EndDate2表示的范围。
给定两个日期范围,确定两个日期是否重叠的最简单或最有效的方法是什么?
例如,假设我们有由DateTime变量StartDate1到EndDate1和StartDate2到EndDate2表示的范围。
当前回答
记住解决方案的一个简单方法是最小(结束)>最大(开始)
其他回答
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。
这里有一个可以在本地使用的通用方法。
// Takes a list and returns all records that have overlapping time ranges.
public static IEnumerable<T> GetOverlappedTimes<T>(IEnumerable<T> list, Func<T, bool> filter, Func<T,DateTime> start, Func<T, DateTime> end)
{
// Selects all records that match filter() on left side and returns all records on right side that overlap.
var overlap = from t1 in list
where filter(t1)
from t2 in list
where !object.Equals(t1, t2) // Don't match the same record on right side.
let in1 = start(t1)
let out1 = end(t1)
let in2 = start(t2)
let out2 = end(t2)
where in1 <= out2 && out1 >= in2
let totover = GetMins(in1, out1, in2, out2)
select t2;
return overlap;
}
public static void TestOverlap()
{
var tl1 = new TempTimeEntry() { ID = 1, Name = "Bill", In = "1/1/08 1:00pm".ToDate(), Out = "1/1/08 4:00pm".ToDate() };
var tl2 = new TempTimeEntry() { ID = 2, Name = "John", In = "1/1/08 5:00pm".ToDate(), Out = "1/1/08 6:00pm".ToDate() };
var tl3 = new TempTimeEntry() { ID = 3, Name = "Lisa", In = "1/1/08 7:00pm".ToDate(), Out = "1/1/08 9:00pm".ToDate() };
var tl4 = new TempTimeEntry() { ID = 4, Name = "Joe", In = "1/1/08 3:00pm".ToDate(), Out = "1/1/08 8:00pm".ToDate() };
var tl5 = new TempTimeEntry() { ID = 1, Name = "Bill", In = "1/1/08 8:01pm".ToDate(), Out = "1/1/08 8:00pm".ToDate() };
var list = new List<TempTimeEntry>() { tl1, tl2, tl3, tl4, tl5 };
var overlap = GetOverlappedTimes(list, (TempTimeEntry t1)=>t1.ID==1, (TempTimeEntry tIn) => tIn.In, (TempTimeEntry tOut) => tOut.Out);
Console.WriteLine("\nRecords overlap:");
foreach (var tl in overlap)
Console.WriteLine("Name:{0} T1In:{1} T1Out:{2}", tl.Name, tl.In, tl.Out);
Console.WriteLine("Done");
/* Output:
Records overlap:
Name:Joe T1In:1/1/2008 3:00:00 PM T1Out:1/1/2008 8:00:00 PM
Name:Lisa T1In:1/1/2008 7:00:00 PM T1Out:1/1/2008 9:00:00 PM
Done
*/
}
此处发布的解决方案不适用于所有重叠范围。。。
----------------------|-------A-------|---------------------- |----B1----| |----B2----| |----B3----| |----------B4----------| |----------------B5----------------| |----B6----| ----------------------|-------A-------|---------------------- |------B7-------| |----------B8-----------| |----B9----| |----B10-----| |--------B11--------| |----B12----| |----B13----| ----------------------|-------A-------|----------------------
我的工作解决方案是:
AND ( ('start_date' BETWEEN STARTDATE AND ENDDATE) -- caters for inner and end date outer OR ('end_date' BETWEEN STARTDATE AND ENDDATE) -- caters for inner and start date outer OR (STARTDATE BETWEEN 'start_date' AND 'end_date') -- only one needed for outer range where dates are inside. )
如果您提供一个日期范围作为输入,并希望找出它是否与数据库中的现有日期范围重叠,则以下条件可以成功满足您的需求
假设您从表单输入中提供了@StartDate和@EndDate。
条件是:
如果@StartDate在existingStartDate之前,而在existing EndDate之后,那么我们可以说@StartDate's在现有日期范围的中间,因此我们可以断定它将重叠
@StartDate >=existing.StartDate And @StartDate <= existing.EndDate)
如果@StartDate在现有StartDate之后,而@EndDate在现有的StartDate之前,我们可以说它将重叠
(@StartDate <= existing.StartDate And @EndDate >= existing.StartDate)
如果@StartDate晚于现有的StartDate,而@EndDate先于现有的EndDate,我们可以得出结论,所提供的日期范围吞噬了现有的日期范围,因此重叠
(@StartDate <= existing.StartDate And @EndDate >= existing.EndDate))
如果任何条件成立,则提供的日期范围与数据库中的现有日期范围重叠。
这里是我的简化。假设时间间隔
| |
| |
不要重叠,xa<xb和ya<yb可以简化处理。上述条件可以简单检查。然后你会得到
ya yb
|--------|
xa |--|xb
|----|
|----|
ya > xa => return ya - xa < xb - xa
else => return xa < yb
正如您可能注意到的,第二个间隔仅在xa>=ya的情况下相关。