If dtEngine.GetChanges Is Nothing Then
            MsgBox("No changes")
        Else
            MsgBox("Changes made")
        End If

Gruß
Christoph

    Private Sub frmMain_FormClosing(sender As Object, e As _
      System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        Dim IsEqual As Boolean = True
        For i = 0 To dtEngine.Rows.Count - 1
            If Not dtEngine.Rows(i).Item(2).Equals(dtUndo.Rows(i).Item(2)) Or _
              Not dtEngine.Rows(i).Item(3).Equals(dtUndo.Rows(i).Item(3)) Then
                IsEqual = False
            End If
        Next
 
        If IsEqual = False Then
            Dim Answer As MsgBoxResult
            Answer = MsgBox("You have made changes. Do you want to save the" & _
              "changes?", MsgBoxStyle.YesNo, "Changes made")
            If Answer = MsgBoxResult.Yes Then
                MsgBox("Saving")
            End If
        End If
 
    End Sub

________
Alle Angaben ohne Gewähr. Keine Haftung für Vorschläge, Tipps oder sonstige Hilfe, falls es schiefgeht, nur Zeit verschwendet oder man sonst nicht zufrieden ist

                            Dim dp As New DataPoint
 
                            dp.XValue = CInt(dtEngine.Rows(i).Item(0))     ' RPM
                            dp.YValues = {CInt(dtEngine.Rows(i).Item(3))}  ' HP

Private Sub TableRelation()
 
    Dim dt1 As New DataTable
 
    dt1.Columns.Add("RPM", GetType(Integer))
    dt1.Columns.Add("Sound", GetType(String))
 
    With dt1.Rows
         .Add(1000, "surr")
         .Add(1200, "brumm")
         .Add(1500, "brumm")
         .Add(2500, "pfeif")
         .Add(4000, "rassel")
         .Add(5000, "schepper")
         .Add(6000, "kaputt")
    End With
 
    dt1.PrimaryKey = {dt1.Columns("RPM")} 'eindeutiger Schlüssel
 
    Dim dt2 As New DataTable
 
    dt2.Columns.Add("RPM_2", GetType(Integer))
    dt2.Columns.Add("Sound", GetType(String))
 
    With dt2.Rows
       .Add(2500, "brumm")
       .Add(4000, "quietsch")
       .Add(6000, "jaul")
       .Add(1500, "surr")
       .Add(1200, "surr")
       .Add(1000, "surr")
    End With
 
    dt2.PrimaryKey = {dt2.Columns("RPM_2")} 'eindeutiger Schlüssel
 
    'gemeinsames Dataset
    Dim ds As New DataSet("RPM_Set")
 
    ds.Tables.Add(dt1) : ds.Tables.Add(dt2)
 
    'Beziehung zwischen Tabellen über eine Datarelation
    Dim dr As New DataRelation _
        ("RPM_Relation", dt1.Columns("RPM"), dt2.Columns("RPM_2"), True)
    ds.Relations.Add(dr)
 
 
    For r1 As Integer = 0 To dt1.Rows.Count - 1
        'korrespondierende Zeilen zur r-Zeile in dt1 '
        'per Relation aus dt2 abfragen
        Dim rows_in_dt2 As DataRow() = dt1.Rows(r1).GetChildRows(dr)
        If rows_in_dt2.Count = 0 Then
           Console.WriteLine _
           (dt1.Rows(r1)("RPM").ToString & _
            " keine Entsprechung in Tabelle 2")
        Else
           For rc As Integer = 0 To rows_in_dt2.Count - 1
              Console.WriteLine _
              (dt1.Rows(r1)("RPM").ToString & "--->" & _
               rows_in_dt2(rc)("Sound").ToString)
           Next rc 'Childrows zur row r1 ind dt1
        End If
    Next r1
 
End Sub