检查表是否包含重叠的时间跨度

Question

我有一个包含两列 FromDate 和 ToDate 的数据表，它们是字符串格式。 我想检查我的表中是否有任何重复的记录。即

From Date    To Date
----------------------      
9/01/2012    9/16/2012   
8/23/2012    8/24/2012   
8/25/2012    8/25/2012   
8/5/2012     8/6/2012    
8/26/2012    8/27/2012   
9/15/2012    9/23/2012

该表包含重复记录，因为它们的日期范围映射为

From Date       To Date      
----------------------      
9/01/2012    9/16/2012   
9/15/2012    9/23/2012

它应该返回 false。

Answer 1

使用DataTable.Search() 方法找出您的DataTable 中是否存在任何记录，这样您就可以在您的记录中强制执行唯一性。

类似的东西

string expression;
expression = "FromDate = #9/01/2012# AND ToDate = #9/16/2012#";
DataRow[] foundRows;

// Use the Select method to find all rows matching the filter.
foundRows = table.Select(expression);

if(foundRows.Length > 0)
     // Show duplicate message
else
    // Insert your new dates

了解更多Go here

Answer 2

尝试解析“To Date”列，并为每个列在“From Date”列中搜索具有较晚对应“To Date”的任何较早日期。

Answer 3

按ToDate、FromDate 排序（或将排序后的索引数组构建到您的数据表中）。从行或数组位置 #2 循环到末尾，查看 FromDate

你也可以按FromDate、ToDate排序，做类似的逻辑。

Answer 4

var query = from row in dt.AsEnumerable()
            from row1 in dt.AsEnumerable()
            where
            (

                 (
                     DateTime.Parse(row1.Field<string>("fromDate")) >= DateTime.Parse(row.Field<string>("fromDate")) &&
                     DateTime.Parse(row1.Field<string>("fromDate")) <= DateTime.Parse(row.Field<string>("toDate"))
                 )
                 ||
                 (
                     DateTime.Parse(row1.Field<string>("toDate")) >= DateTime.Parse(row.Field<string>("fromDate")) &&
                     DateTime.Parse(row1.Field<string>("toDate")) <= DateTime.Parse(row.Field<string>("toDate"))
                 )
            )
            select new
            {
                fromDate = DateTime.Parse(row1.Field<string>("fromDate")),
                toDate = DateTime.Parse(row1.Field<string>("toDate"))
            };
//This lst contains the dates which are overlapping    
var lst = query.Distinct().ToList();

Answer 5

那么，selfjoin 在这里会有所帮助：

我有一个小班TimePeriod，只是为了满足你的需要

public class TimePeriod
{
    public int Id;
    public DateTime FromDate { get; set; }

    public DateTime ToDate { get; set; }

    public static DateTime Parse(string date)
    {
        var dt = DateTime.Parse(date, 
        CultureInfo.CreateSpecificCulture("en-US"), DateTimeStyles.RoundtripKind);
        return dt;
    }
}

然后我有一些测试数据

var list = new List();

        list.Add(new TimePeriod() { Id = 1, FromDate = TimePeriod.Parse("9/01/2012"),  ToDate = TimePeriod.Parse("9/16/2012") });
        list.Add(new TimePeriod() { Id = 2, FromDate = TimePeriod.Parse("8/23/2012"), ToDate = TimePeriod.Parse("8/24/2012") });
        list.Add(new TimePeriod() { Id = 3, FromDate = TimePeriod.Parse("8/25/2012"), ToDate = TimePeriod.Parse("8/25/2012") });
        list.Add(new TimePeriod() { Id = 4, FromDate = TimePeriod.Parse("8/5/2012"), ToDate = TimePeriod.Parse("8/6/2012") });
        list.Add(new TimePeriod() { Id = 5, FromDate = TimePeriod.Parse("8/26/2012"), ToDate = TimePeriod.Parse("8/27/2012") });
        list.Add(new TimePeriod() { Id = 6, FromDate = TimePeriod.Parse("9/15/2012"), ToDate = TimePeriod.Parse("9/23/2012") });

这是解决方案：（受到 OraNob 的启发，谢谢）

var overlaps = from current in list
            from compare in list
            where
            (
            (compare.FromDate > current.FromDate &&
            compare.FromDate < current.ToDate) ||
            (compare.ToDate > current.FromDate &&
            compare.ToDate < current.ToDate)
            )
            select new
            {
                Id1 = current.Id,
                Id2 = compare.Id,
            };

也许你想省略第二个 ID（因为你会有重复的 这里（1 / 6）和（6 / 1）

Answer 6

如果您处理大型数据表，您应该使用@ErikE 响应。 这需要更多的代码行，但绝对是迄今为止最有效的。

如果它的小表并且您更喜欢比较每两行。 您可以使用其他建议。 只需确保防止行与其自身进行比较，并在结果枚举中重复。

var query = from x in list
            where list.Exists((y) => x != y &&
                                     x.FromDate <= y.ToDate &&
                                     y.FromDate <= x.ToDate)
            select x;

Answer 7

strong textDeclare @Table Table  
(  
    RowId Int Identity(1, 1) Not Null, 
      Id NChar(3) Not Null, 
      StartDate DATETIME Not Null, 
      EndDate DATETIME Not Null 
);  

Insert Into @Table (Id, StartDate, EndDate)  
Select 'id1', '20131210 10:10', '20131220 10:10' Union All  
Select 'id1', '20131211', '20131215' Union All  
Select 'id1', '20131201', '20131205' Union All  
Select 'id1', '20131206', '20131208' Union All  
Select 'id1', '20131225 10:10', '20131225 10:11'
Select *  
From @Table;  


With Overlaps (OverlapRowId, BaseRowId, OStart, OEnd, BStart, BEnd)  
As  
(  
        Select Overlap.RowId, Base.RowId, Overlap.StartDate, Overlap.EndDate, Base.StartDate, Base.EndDate 
        From @Table As Base  
        Inner Join @Table As Overlap On Overlap.Id = Base.Id  
        Where (((Overlap.StartDate > Base.StartDate) And (Overlap.StartDate < Base.EndDate))
          Or ((Overlap.StartDate = Base.StartDate) And (Overlap.EndDate > Base.EndDate))) 
          And (Base.RowId != Overlap.RowId) 
) 
-- Remove records that were found to cause overlap issues.  
Delete T  
From @Table As T  
Inner Join  
(  
        Select O.OverlapRowId   
        From Overlaps As O 
        Left Join Overlaps As Fp On Fp.OverlapRowId = O.BaseRowId  
        Where (Fp.OverlapRowId Is Null) 
) As SubQuery On SubQuery.OverlapRowId = T.RowId;  

-- Select the valid options.  
Select RowId, Id, StartDate, EndDate  
From @Table where StartDate<EndDate;  
Go