how to merge rows in datatable which had same value (VB) - asp.net

Question

I have one datatable tempDT with value :
Serial_No testong
---------------------------------------
DTSHCSN001205035919201 [ OUT ] <br/> Partner : 90000032 <br/> Date : 16 Feb 2012
DTSHCSN001205035919201 [ IN ] <br/> Partner : 90000032 <br/> Date : 16 Feb 2012
DTSHCSN001205035919201 [ OUT ] <br/> Partner : 80000869 <br/> Date : 31 Mar 2012
DTSHCSN001205035919201 [ IN ] <br/> Partner : 80000869 <br/> Date : 31 Mar 2012
The problem is I want merge duplicate serial_no into one row which the value of testong adding to new column.
I have tried many ways, but I can't find the solution.
Here is my code behind :
Dim tempDt = GetItemDataTable()
Dim dtData As New DataTable
dtData.Columns.Add("Serial_No")
Dim i As Integer = 0
Dim row As DataRow
For Each row In tempDt.Rows
i += 1
Dim dr As DataRow = dtData.NewRow
dr("Serial_No") = row(0)
If dr("Serial_No") = row(0) Then
Dim colBaru As GridViewDataTextColumn = New GridViewDataTextColumn()
colBaru.Caption = i
colBaru.FieldName = i
colBaru.CellStyle.HorizontalAlign = HorizontalAlign.Center
colBaru.HeaderStyle.HorizontalAlign = HorizontalAlign.Center
colBaru.Width = 150
colBaru.UnboundType = DevExpress.Data.UnboundColumnType.Integer
colBaru.VisibleIndex = grid.VisibleColumns.Count
colBaru.PropertiesTextEdit.DisplayFormatString = "d1"
colBaru.PropertiesTextEdit.EncodeHtml = True
grid.Columns.Add(colBaru)
dtData.Columns.Add(i)
dr(i) = row(3)
dtData.Rows.Add(dr)
Else
dr("Serial_No") = row(0)
dtData.Rows.Add(dr)
End If
When I debug the result is :
But I wanted the result is like this :

Answer 1

I have updated my code, so it would look at the columns rather using variable i
Dim tempDt = GetItemDataTable()
Dim dtData As New DataTable
'initial the first and second columns
dtData.Columns.Add("Serial_No")
dtData.Columns.Add("1")
Dim i As Integer = 0
Dim row As DataRow
For Each row In tempDt.Rows
Dim dr As DataRow
i += 1
'check if the serial no exists in the new Data Table
If dtData.Select("Serial_No='" & row(0) & "'").Length > 0 Then
'If found, then get the existing row
dr = dtData.Select("Serial_No='" & row(0) & "'")(0)
'Create new GridViewDataTextColumn
Dim colBaru As GridViewDataTextColumn = New GridViewDataTextColumn()
colBaru.Caption = i
colBaru.FieldName = i
colBaru.CellStyle.HorizontalAlign = HorizontalAlign.Center
colBaru.HeaderStyle.HorizontalAlign = HorizontalAlign.Center
colBaru.UnboundType = DevExpress.Data.UnboundColumnType.Integer
colBaru.VisibleIndex = grid.VisibleColumns.Count
colBaru.PropertiesTextEdit.DisplayFormatString = "d1"
colBaru.PropertiesTextEdit.EncodeHtml = False
grid.Columns.Add(colBaru)
'I assume you are adding the Number as the columns name
'Only need to create if the Column doesn't exist
If dtData.Columns.count - 1 < i Then
dtData.Columns.Add(i.ToString)
End If
'Use variable i here
dr(i) = row(3)
'Comment this out as you don't need to
'dtData.Rows.Add(dr)
Else
'reset value of i
i = 1
'If not found, then create a new row
dr = dtData.NewRow
' i put this to add the serial_no value to datatable
dr("Serial_No") = row(0)
'for adding first value i with same row as serial_no
Dim colBaru As GridViewDataTextColumn = New GridViewDataTextColumn()
colBaru.Caption = i
colBaru.FieldName = i
colBaru.CellStyle.HorizontalAlign = HorizontalAlign.Center
colBaru.HeaderStyle.HorizontalAlign = HorizontalAlign.Center
colBaru.UnboundType = DevExpress.Data.UnboundColumnType.Integer
colBaru.VisibleIndex = grid.VisibleColumns.Count
colBaru.PropertiesTextEdit.DisplayFormatString = "d1"
colBaru.PropertiesTextEdit.EncodeHtml = False
grid.Columns.Add(colBaru)
'dtData.Columns.Add("1")
'Would be better to use back variable i if you have reset it
dr(i) = row(3)
dtData.Rows.Add(dr)
End If
Next