Kodingan lengkap autonumber

Dim datauser As ADODB.Recordset
Dim kodeid  As ADODB.Recordset
Private Sub AutoNomor()
    Set kodeid = conn.Execute("select * from mahasiswa order by idmahasiswa desc")
        With kodeid
            If .EOF Then
                txtnim.Text = "MHS" & "001"
            Else
                txtnim.Text = "MHS" & Right(Str(Val(Right(.Fields(0), 3)) + 1001), 3)
            End If
        End With
End Sub
Sub aktif()
    txtnama.Enabled = True
    txtjurusan.Enabled = True
    txtnohp.Enabled = True
End Sub
Sub nonaktif()
    txtnim.Enabled = False
    txtnama.Enabled = False
    txtjurusan.Enabled = False
    txtnohp.Enabled = False
End Sub
Sub bersih()
    txtnim.Text = ""
    txtnama.Text = ""
    txtjurusan.Text = ""
    txtnohp.Text = ""
End Sub

Private Sub cmdinput_Click()
    If cmdinput.Caption = "INPUT" Then
        aktif
        cmdinput.Caption = "SIMPAN"
        txtnama.SetFocus
        AutoNomor
    ElseIf cmdinput.Caption = "SIMPAN" Then
        Set datauser = New ADODB.Recordset
        query = "insert into mahasiswa values ('" & txtnim.Text & "', '" & txtnama.Text & "','" & txtjurusan.Text & "','" & txtnohp.Text & "')"
        conn.Execute query
        Set datauser = New ADODB.Recordset
        datauser.Open "select * from mahasiswa", conn
        Set DataGrid1.DataSource = datauser
        MsgBox "Data Berhasil Disimpan"
    End If
End Sub

Private Sub Form_Load()
    bersih
    nonaktif
    Set datauser = New ADODB.Recordset
    datauser.Open "select * from mahasiswa", conn
    Set DataGrid1.DataSource = datauser
End Sub