How to query groupby in following situation

Question

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I have datatable in the following format

Id   LocationId  UserName  Startdate
1       10        xz        2017-02-21 09:05:20
2       10        xz        2017-02-21 09:15:20
3       10        xz        2017-02-21 09:25:20
4       10        xz        2017-02-21 09:35:20
5       11        xz        2017-02-21 09:45:20
6       11        xz        2017-02-21 09:55:20
7       11        xz        2017-02-21 10:05:20
8       11        xz        2017-02-21 10:15:20

I want to calculate starttime end time and differnce of time ,

and have show record as

Id      locationId  startdate          starttime             endtime    timespan   
1            10      2017-02-21          09:05              09:35:20  0hr 30min0sec               
1            10    2017-02-21            09:05             09:35:20   0hr 30min0sec

What I have tried:

VB

<pre> If dt IsNot Nothing AndAlso dt.Rows.Count > 0 Then
            hdnreviewerHistoryCount.Value = UserManager.GetReviewerHistoryByActivityTypeCount(Request.QueryString("Id"), StartDate, EndDate, activity)
            Dim StartTime As New TimeSpan
            Dim EndTime As New TimeSpan
            Dim totalTime As New TimeSpan
            totalTime = Convert.ToDateTime(dt.Rows(dt.Rows.Count - 1)("AddedOn")).Subtract(dt.Rows(0)("AddedOn"))
            Dim index As Integer = 0
            Dim filterdata As New Filterdata
            Dim prevTime As New DateTime
            Dim prevLocation As Integer
            For Each row As DataRow In dt.Rows
                If index = 0 AndAlso row("CheckInLocation") IsNot DBNull.Value Then
                    prevTime = row("AddedOn")
                    prevLocation = row("CheckInLocation")
                Else
                    If prevLocation = row("CheckInLocation") Then
                        Dim timeDiff As TimeSpan = Convert.ToDateTime(row("AddedOn")).Subtract(prevTime)
                        EndTime = EndTime.Add(timeDiff)
                        prevLocation = IIf(row("LocationAddress") Is DBNull.Value, 0, row("LocationAddress"))
                        prevTime = row("AddedOn")
                    Else

                    End If

                End If
                index += 1
            Next
            rptreviewerhistory.DataSource = filterlist
            rptreviewerhistory.DataBind()
        End If
    End Sub
    Public Class Filterdata
        Public Property customdate As DateTime
        Public Property fromdate As DateTime
        Public Property todate As DateTime
        Public Property timespent As DateTime
        Public Property LocationName As String

    End Class

Posted 21-Feb-17 2:37am

Sajid227

Updated 21-Feb-17 9:51am

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Graeme_Grant · Answer 1 · 2017-02-21T02:46:00

Solution 1

If you are pulling data from a database, then you can use the SQL GROUP BY[^]. If you want to do it in code, then you could use Linq's GROUP BY[^] clause.

Posted 21-Feb-17 2:46am

Graeme_Grant

Maciej Los · Answer 2 · 2017-02-21T09:51:00

Try this:

VB.NET

'needed to convert string into date
Dim provider As System.Globalization.CultureInfo = System.Globalization.CultureInfo.InvariantCulture
'create sample datatable
Dim dt As DataTable = New DataTable()
dt.Columns.Add(New DataColumn("Id", Type.GetType("System.Int32")))
dt.Columns.Add(New DataColumn("LocationId", Type.GetType("System.Int32")))
dt.Columns.Add(New DataColumn("UserName", Type.GetType("System.String")))
dt.Columns.Add(New DataColumn("Startdate", Type.GetType("System.DateTime")))
'insert data
dt.Rows.Add(New Object(){1, 10, "xz", DateTime.ParseExact("2017-02-21 09:05:20", "yyyy-MM-dd HH:mm:ss", provider)})
dt.Rows.Add(New Object(){2, 10, "xz", DateTime.ParseExact("2017-02-21 09:15:20", "yyyy-MM-dd HH:mm:ss", provider)})
dt.Rows.Add(New Object(){3, 10, "xz", DateTime.ParseExact("2017-02-21 09:25:20", "yyyy-MM-dd HH:mm:ss", provider)})
dt.Rows.Add(New Object(){4, 10, "xz", DateTime.ParseExact("2017-02-21 09:35:20", "yyyy-MM-dd HH:mm:ss", provider)})
dt.Rows.Add(New Object(){5, 11, "xz", DateTime.ParseExact("2017-02-21 09:45:20", "yyyy-MM-dd HH:mm:ss", provider)})
dt.Rows.Add(New Object(){6, 11, "xz", DateTime.ParseExact("2017-02-21 09:55:20", "yyyy-MM-dd HH:mm:ss", provider)})
dt.Rows.Add(New Object(){7, 11, "xz", DateTime.ParseExact("2017-02-21 10:05:20", "yyyy-MM-dd HH:mm:ss", provider)})
dt.Rows.Add(New Object(){8, 11, "xz", DateTime.ParseExact("2017-02-21 10:15:20", "yyyy-MM-dd HH:mm:ss", provider)})

'group data by LocationId and UserName
'calculate time difference
Dim result = dt.AsEnumerable() _
	.GroupBy(Function(x) New With { _
			.LocationId=x.Field(Of Integer)("LocationId"), _
			.UserName=x.Field(Of String)("UserName")}) _
	.Select(Function(grp) New With _
		{ _
			.LocationId = grp.Key.LocationId, _
			.UserName = grp.Key.UserName, _
			.StartTime = grp.Select(Function(a) a.Field(Of DateTime)("StartDate")).Min().ToString("HH:mm:ss"), _
			.EndTime = grp.Select(Function(a) a.Field(Of DateTime)("StartDate")).Max().ToString("HH:mm:ss"), _
			.TimeDiff = grp.Select(Function(a) a.Field(Of DateTime)("StartDate")).Max() - grp.Select(Function(a) a.Field(Of DateTime)("StartDate")).Min() _
		}) _
	.ToList()

Above should return:

LocationId UserName StartTime EndTime  TimeDiff
10         xz       09:05:20  09:35:20 00:30:00 
11         xz       09:45:20  10:15:20 00:30:00