How to iterate between two datatables in ASP.NET - asp.net

Question

I have two datatables (dtSF and CurveFitTable) that contain two different values which I have to multiply. The objective is to produce a datatable that contains the product of two values from two different datatables. The twist is, the CurveFitTable came from different csv files in a directory which I already defined.
What I intended to do is to have a datatable like the adjustedCopy table in the image below. Unfortunately, what I'm getting is a single datatable which kept on being overwritten and whenever I attempt to databind it to the grid, the datatable seems to be empty. Please help. T.T
This is my code:
Dim adjusteddemandtable As New DataTable()
Dim adjustedcopy As New DataTable()
Dim multiply_SF As Double
Dim adjusted_Demand As Double
Dim initial_Demand As Double
Dim basecurvestamp As Date
adjusteddemandtable.Columns.Add("Base Curve", GetType(Date))
adjusteddemandtable.Columns("Base Curve").SetOrdinal(0)
adjusteddemandtable.Columns.Add("Adjusted_Demand", GetType(Double))
Dim CurveFitTatble As New DataTable()
Try
For Each filename As String In System.IO.Directory.GetFiles(BackUpDirectory)
CurveFitTatble = GetDataTabletFromCSVFile(filename)
For Each row2 As DataRow In dtSF.Rows()
For Each row As DataRow In CurveFitTatble.Rows()
initial_Demand = row(1)
basecurvestamp = row(0)
multiply_SF = row2(0)
adjusted_Demand = multiply_SF * initial_Demand
Dim rowa As DataRow = adjusteddemandtable.Rows.Add()
rowa(0) = basecurvestamp
rowa(1) = adjusted_Demand
Next
Next
adjustedcopy.Merge(adjusteddemandtable, True, MissingSchemaAction.AddWithKey)
Next
GridView1.DataSource = adjustedcopy
GridView1.DataBind()
Catch ex As Exception
ErrorMessageBox(ex.Message)
End Try
I think, I'm missing something or overlooked an important step. Please advise. Thanks in advance.

Answer 1

I just did what #jmcilhinney told me (that is to replace nested Foreach nested loop. Here is my new code (and fortunately, it is working as its expected output requires)
Try
Dim y As Integer = System.IO.Directory.GetFiles(BackUpDirectory).Length
Dim row1 As DataRow
Dim i As Integer = 0
While i < y
row1 = dtSF.Rows(i)
Dim filenames As String() = System.IO.Directory.GetFiles(BackUpDirectory)
Dim filename As String = filenames(i)
multiply_SF = row1(0)
CurveFitTatble = New DataTable()
Dim TS_Name As String = "TmeStamp" + "_" & i
Dim AD_Name As String = "AdjustedDemand" + "_" & i
If i = 0 Then
adjusteddemandtable.Columns.Add(TS_Name, GetType(Date))
adjusteddemandtable.Columns(TS_Name).SetOrdinal(i)
adjusteddemandtable.Columns.Add(AD_Name, GetType(Double))
adjusteddemandtable.Columns(AD_Name).SetOrdinal(i + 1)
ElseIf i > 0 Then
adjusteddemandtable.Columns.Add(TS_Name, GetType(Date))
adjusteddemandtable.Columns(TS_Name).SetOrdinal(i + 1)
adjusteddemandtable.Columns.Add(AD_Name, GetType(Double))
adjusteddemandtable.Columns(AD_Name).SetOrdinal(i + 2)
End If
'If row1(0) = filename Then
CurveFitTatble = GetDataTabletFromCSVFile(filename)
'For Each row As DataRow In CurveFitTatble.Rows()
Dim row As DataRow
For j As Integer = 0 To CurveFitTatble.Rows.Count - 1
row = CurveFitTatble.Rows(j)
initial_Demand = row(1)
basecurvestamp = row(0)
adjusted_Demand = multiply_SF * initial_Demand
Dim rowa As DataRow = adjusteddemandtable.Rows.Add()
If i = 0 Then
rowa(i) = basecurvestamp
rowa(i + 1) = adjusted_Demand
ElseIf i > 0 Then
rowa(i + 1) = basecurvestamp
rowa(i + 2) = adjusted_Demand
End If
Next
i = i + 1
End While
Catch ex As Exception
ErrorMessageBox(ex.Message)
End Try