จะ update access database จาก datagridview ที่ดึงมาจากไฟล์ Excel อย่างไรครับ

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Try
            con.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Program Files\xxxx\xxxx.mdb"
            cmd.Connection = con
            Dim Count As Integer = 0
            con.Open()
            For Count = 0 To DataGridView1.Rows.Count - 1
                Dim dr As New DataGridViewRow
                dr = DataGridView1.Rows(Count)
                cmd.CommandText = "update StudentGrade set grade = '" & dr.Cells(5).Value & "' where studentid = " & dr.Cells(0).Value & "AND subjectcode = " & dr.Cells(2).Value
            Next
            MessageBox.Show("บันทึกข้อมูลแล้ว")
            con.Close()
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
    End Sub