Oracle独自の“変更通知機能”で同時実行性を向上：.NETユーザー必見！ Oracle 10gのお作法（5）（3/3 ページ）

' イベント（Notification）が発生したときの処理
Private Sub OnMyNotification(ByVal sender As Object, _
  ByVal args As OracleNotificationEventArgs)
    'OracleNotificationEventArgsのROWIDを基に、変更行データを取得
    For Each detailRow As DataRow In args.Details.Rows
        Dim rowid As String = detailRow("Rowid").ToString
        Dim sqlupdate = _
"SELECT emp.*, emp.rowid FROM emp WHERE rowid = '" + rowid + "'"
        Dim con2 As New OracleConnection("USER ID=scott;DATA SOURCE=
ORCL10GR2;PASSWORD=tiger;PERSIST SECURITY INFO=true;")
        Dim cmd2 As New OracleCommand(sqlupdate, con2)
        con2.Open()
        Dim dr2 As OracleDataReader = cmd2.ExecuteReader
        Dim iRow As Integer
        If dr2.Read Then
            'OracleNotificationEventArgs.ResourceNamesより
            'オブジェクト名を取得
            Dim msgtitle As String = _
args.ResourceNames(0).ToString + "が変更されました"
            Dim msgdesc As String = _
"EMPNO=" + dr2("empno").ToString + " ENAME=" + dr2("ename").ToString _
            + "が変更されました。" & vbNewLine & "表示を更新しますか？"
 
            'ボタンはYesNoかつモーダル表示
            If MsgBox(msgdesc, _
MsgBoxStyle.YesNo + MsgBoxStyle.SystemModal, msgtitle) = _
DialogResult.Yes Then
                For iRow = 0 To gvEmp.Rows.Count - 1
                    If gvEmp.Rows(iRow).Cells(0).Value = _
dr2("empno").ToString Then
                        gvEmp.Rows(iRow).Selected = True
                        Exit For
                    End If
                Next
                '更新されたデータをDataGridViewに表示
                empOracleDataAdapter1.Fill(Emp1.Emp)
            End If
        End If
        con2.Close()
    Next
End Sub