Validasi KeyPress

Private Sub txtUsername_KeyPress(sender As Object, e As KeyPressEventArgs) Handles txtUsername.KeyPress

        'tampung hasil query ke datatable
        Dim DT As New DataTable
        Using con As New MySqlConnection("server=localhost;database=tes;uid=root;pwd=root;")
            Using adp As New MySqlDataAdapter("Select username, password From Login", con)
                Try
                    adp.Fill(DT)
                Catch ex As Exception
                    MsgBox(ex.ToString)
                    Exit Sub
                End Try
            End Using
        End Using

        'validasi jika user menekan tombol enter di textbox username
        If e.KeyChar = Chr(13) Then
            If txtUsername.Text = "" Then
                MsgBox("Masukan username anda", vbInformation, "Kesalahan")
                txtUsername.Focus()
            Else

                'filter/seleksi datatable
                If DT.Select("username='" & txtUsername.Text & "' ").Count > 0 Then
                    txtPassword.Focus()
                Else
                    MsgBox("Username tidak ditemukan", vbInformation, "Kesalahan")
                    txtUsername.Focus()
                End If
            End If

        End If


    End Sub