在退出执行代码之前

Question

我需要在退出aspx网页之前将列onoffline设置为“off”。

我尝试在Page.Unload中放入Global.aspx.vb中的两个位置：Session_End和Application_End但是没有一个在“onoffline”列中放置“off”。

    ' To Fire when the session ends
    Dim connStr, cmdStr As String
    Try
        connStr = "connection string works"
        cmdStr = "UPDATE [sessionregister] SET [onoffline]=@onoffline;"
        Using conn As New SqlConnection(connStr)
            Using cmd As New SqlCommand(cmdStr, conn)
                conn.Open()
                cmd.Parameters.AddWithValue("@onoffline", "off")
                cmd.ExecuteNonQuery()
                conn.Close()
                cmd.Dispose()
                conn.Dispose()
            End Using
        End Using
    Catch ex As Exception
        Console.WriteLine(ex.Message)
    End Try