[asp.net] สอบถามวิธีสร้าง onclick บน calendar และปัญหาข้อมูลที่แสดงในcalendarซ้ำ (ใช้ OnDayRender วนลูปจากฐานข้อมูล)

<asp:Calendar ID="Calendar1" runat="server" FirstDayOfWeek="Sunday" style="margin-top: 0px"
        OnDayRender="Calendar1_Dayrender"
        CssClass="theme1" 
        OtherMonthDayStyle-BackColor="WhiteSmoke" OtherMonthDayStyle-ForeColor="WhiteSmoke" ShowDayHeader="true" >
    </asp:Calendar>

  Sub Calendar1_Dayrender(ByVal sender As Object, ByVal e As DayRenderEventArgs) Handles Calendar1.DayRender
        Dim objConn As New SqlClient.SqlConnection
        Dim objCmd As New SqlClient.SqlCommand
        Dim dtAdapter As New SqlClient.SqlDataAdapter
        Dim ds As New DataSet
        Dim strConnString, strSQL As String

        strConnString = ConfigurationManager.ConnectionStrings("ConnectionString").ConnectionString
        strSQL = "SELECT * FROM Pdata"

        objConn.ConnectionString = strConnString
        With objCmd
            .Connection = objConn
            .CommandText = strSQL
            .CommandType = CommandType.Text
        End With
        dtAdapter.SelectCommand = objCmd
        dtAdapter.Fill(ds)
        dtAdapter = Nothing

        For Each dr As DataRow In ds.Tables(0).Rows
           
            Dim sc As String = dr("Pno")
            Dim startDate As Date
            startDate = dr("PDate")

          
            If e.Day.Date = startDate Then
                e.Cell.BackColor = System.Drawing.Color.DarkGreen
                e.Cell.Controls.Add(New LiteralControl(ChrW(60) & "br" & ChrW(62) & sc))
                sc = ""
                '   Continue For
                Exit For

            End If
        Next

    End Sub