Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button4.Click
        Dim sCon As String = ("Provider=Microsoft.Jet.OLEDB.4.0;Data" & _
        "Source=db.MDB")
        Dim cn As New OleDb.OleDbConnection(scon)
        Dim sSql As String = "SELECT SUM({STUNDEN}) AS Summe FROM {TABLE}"
        Dim cmd As New OleDb.OleDbCommand(sSql, cn)
        cmd.Connection.Open()
        Dim sum As Integer = CInt(cmd.ExecuteScalar())
        cmd.Connection.Close()
        Debug.WriteLine(sum.ToString)
    End Sub

    Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button5.Click
        Dim sCon As String = ("Provider=Microsoft.Jet.OLEDB.4.0;Data" & _
        "Source=db.MDB")
        Dim cn As New OleDb.OleDbConnection(sCon)
        Dim sSql As String = "SELECT * FROM Test"
        Dim da As New OleDb.OleDbDataAdapter(sSql, cn)
        Dim dt As New DataTable
        da.Fill(dt)
        Dim sum As Integer = CInt(dt.Compute("SUM({STUNDEN})", String.Empty)) 
        Debug.WriteLine(sum.ToString)
    End Sub