ถามเรื่อง ComboBox DataBinding (vb2005+ Access 2003)

<%@ Import Namespace="System.Data"%>
<%@ Import Namespace="System.Data.OleDb"%>
<%@ Page Language="VB" %>
<script runat="server">

    Sub Page_Load(sender As Object, e As EventArgs)
		IF Not Page.IsPostBack() Then
			DropDownListDataTable()
			DropDownListDataTableRows()
			DropDownListSortedList()
			DropDownListAddInsertItem()
		End IF
    End Sub

	'*** DropDownList & DataTable ***'
	Function DropDownListDataTable()
		Dim objConn As OleDbConnection
		Dim dtAdapter As OleDbDataAdapter 
		Dim dt As New DataTable
			  
		Dim strConnString As String
		strConnString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source="& _
		Server.MapPath("database/mydatabase.mdb")&";"
		objConn = New OleDbConnection(strConnString)
		objConn.Open()

		Dim strSQL As String		
		strSQL = "SELECT * FROM country"

		dtAdapter = New OleDbDataAdapter(strSQL, objConn)
		dtAdapter.Fill(dt)

		dtAdapter = Nothing
		objConn.Close()
		objConn = Nothing

		'*** DropDownlist ***'
		With Me.myDDL1
			.DataSource = dt
			.DataTextField = "CountryName"
			.DataValueField = "CountryCode"
			.DataBind()
		End With
		
		'*** Default Value ***'
		myDDL1.SelectedIndex = myDDL1.Items.IndexOf(myDDL1.Items.FindByValue("TH"))  '*** By DataValueField ***'
		'myDDL1.SelectedIndex = myDDL1.Items.IndexOf(myDDL1.Items.FindByText("Thailand"))  '*** By DataTextField ***'

	End Function

	'*** DropDownList & TableRows ***'
	Sub DropDownListDataTableRows()
        Dim dt As New DataTable
        Dim dr As DataRow
		
		'*** Column ***'
        dt.Columns.Add("Sex")
        dt.Columns.Add("SexDesc")
		
		'*** Rows ***'
		dr = dt.NewRow
        dr("Sex") = "M"
        dr("SexDesc") = "Man"
        dt.Rows.Add(dr)

		'*** Rows ***'
		dr = dt.NewRow
        dr("Sex") = "W"
        dr("SexDesc") = "Woman"
        dt.Rows.Add(dr)

		'*** DropDownlist ***'
		With Me.myDDL2
				.DataSource = dt
				.DataTextField = "SexDesc"
				.DataValueField = "Sex"
				.DataBind()
		End With

		'*** Default Value ***'
		myDDL2.SelectedIndex = myDDL2.Items.IndexOf(myDDL2.Items.FindByValue("W"))  '*** By DataValueField ***'
		'myDDL2.SelectedIndex = myDDL2.Items.IndexOf(myDDL2.Items.FindByText("Woman"))  '*** By DataTextField ***'

	End Sub

	'*** DropDownList & SortedList ***'
	Sub DropDownListSortedList()
        Dim mySortedList AS New SortedList 
		
		mySortedList.Add("M","Man")
		mySortedList.Add("W","Woman")

		'*** DropDownlist ***'
		  With Me.myDDL3
				.DataSource = mySortedList
				.DataTextField = "Value"
				.DataValueField = "Key"
				.DataBind()
		  End With

		'*** Default Value ***'
		myDDL3.SelectedIndex = myDDL3.Items.IndexOf(myDDL3.Items.FindByValue("W"))  '*** By DataValueField ***'
		'myDDL3.SelectedIndex = myDDL3.Items.IndexOf(myDDL3.Items.FindByText("Woman"))  '*** By DataTextField ***'
	End Sub

	'*** Add/Insert Items ***'
	Sub DropDownListAddInsertItem()
        Dim mySortedList AS New SortedList 
		
		mySortedList.Add("M","Man")
		mySortedList.Add("W","Woman")

		'*** DropDownList ***'
		With Me.myDDL4
			.DataSource = mySortedList
			.DataTextField = "Value"
			.DataValueField = "Key"
			.DataBind()
		End With
		
		'*** Add & Insert New Item ***'
		Dim strText,strValue As String

		'*** Insert Item ***'
		strText = ""
		strValue = ""
		Dim InsertItem As New ListItem(strText, strValue)
		myDDL4.Items.Insert(0, InsertItem)

		'*** Add Items ***'		
		strText = "Guy"
		strValue = "G"
		Dim AddItem As New ListItem(strText, strValue)
		myDDL4.Items.Add(AddItem)

		'*** Default Value ***'
		myDDL4.SelectedIndex = myDDL4.Items.IndexOf(myDDL4.Items.FindByValue(""))  '*** By DataValueField ***'
		'myDDL4.SelectedIndex = myDDL4.Items.IndexOf(myDDL4.Items.FindByText(""))  '*** By DataTextField ***'
	End Sub

    Sub Button1_OnClick(sender as Object, e As EventArgs)
        Me.lblText1.Text = Me.myDDL1.SelectedItem.Value  '*** Or Me.myDDL1.SelectedItem.Text ***'
		Me.lblText2.Text = Me.myDDL2.SelectedItem.Value  '*** Or Me.myDDL2.SelectedItem.Text ***'
		Me.lblText3.Text = Me.myDDL3.SelectedItem.Value  '*** Or Me.myDDL3.SelectedItem.Text ***'
		Me.lblText4.Text = Me.myDDL4.SelectedItem.Value  '*** Or Me.myDDL4.SelectedItem.Text ***'
    End Sub

</script>
<html>
<head>
<title>ThaiCreate.Com ASP.NET - DropDownlist & DataBind</title>
</head>
<body>
	<form id="form1" runat="server">
		<asp:DropDownList id="myDDL1" runat="server"></asp:DropDownList> 
		<asp:DropDownList id="myDDL2" runat="server"></asp:DropDownList>
		<asp:DropDownList id="myDDL3" runat="server"></asp:DropDownList>
		<asp:DropDownList id="myDDL4" runat="server"></asp:DropDownList>
		<asp:Button id="Button1" onclick="Button1_OnClick" runat="server" Text="Button"></asp:Button>
		<hr />
		<asp:Label id="lblText1" runat="server"></asp:Label><br />
		<asp:Label id="lblText2" runat="server"></asp:Label><br />
		<asp:Label id="lblText3" runat="server"></asp:Label><br />
		<asp:Label id="lblText4" runat="server"></asp:Label><br />
	</form>
</body>
</html>