Pagina aspx
codice:
<%@ Page Language="vb" AutoEventWireup="false" Codebehind="popolare_dropdownlist.aspx.vb" Inherits="corso_apogeo.popolare_dropdownlist"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
	<HEAD>
		<title>popolare_dropdownlist</title>
		<meta content="Microsoft Visual Studio.NET 7.0" name="GENERATOR">
		<meta content="Visual Basic 7.0" name="CODE_LANGUAGE">
		<meta content="JavaScript" name="vs_defaultClientScript">
		<meta content="http://schemas.microsoft.com/intellisense/ie5" name="vs_targetSchema">
		<LINK href="../Stile_celeste.css" type="text/css" rel="stylesheet">
		<script id="clientEventHandlersJS" language="javascript">
<!--

function provincie_onchange() {
	var v = document.Form1.provincie;
	var testo = (v.options[v.selectedIndex].text);
	var valore = (v.options[v.selectedIndex].value);
	
	document.getElementById("Label2").innerText = "Hai scelto: Provincia = " + testo + ", ID = " + valore;
}

//-->
		</script>
	</HEAD>
	<body>
		<form id="Form1" method="post" runat="server">
			

Scegli una provincia: 
				<asp:dropdownlist id="provincie" runat="server" DataValueField="id_provincia" DataTextField="nome"></asp:dropdownlist>
				

				

				<asp:Button id="Button1" runat="server" Text="Button"></asp:Button></P>
			


				<asp:Label id="Label1" runat="server"></asp:Label></P>
		</form>
		<span id="Label2" style="BORDER-RIGHT: red 1px solid; BORDER-TOP: red 1px solid; BORDER-LEFT: red 1px solid; BORDER-BOTTOM: red 1px solid"></span>
	</body>
</HTML>
Codebehind:
codice:
Public Class popolare_dropdownlist
    Inherits System.Web.UI.Page
    Protected WithEvents Button1 As System.Web.UI.WebControls.Button
    Protected WithEvents Label1 As System.Web.UI.WebControls.Label
    Protected WithEvents provincie As System.Web.UI.WebControls.DropDownList

#Region " Codice generato da Progettazione Web Form "

    'Chiamata richiesta da Progettazione Web Form.
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()

    End Sub

    Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init
        'CODEGEN: questa chiamata al metodo è richiesta da Progettazione Web Form.
        'Non modificarla nell'editor del codice.
        InitializeComponent()
    End Sub

#End Region

    Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'Inserire qui il codice utente necessario per inizializzare la pagina
        If Not Page.IsPostBack Then
            Me.PopolaProvincie()
        End If

    End Sub

    Protected Sub PopolaProvincie()
        Dim sql$ = "SELECT * FROM PROVINCE"
        Dim StringaConnessione$ = "File Name=C:\Documenti\Interdev\Prova_Access.UDL"
        Dim Connessione As New OleDbConnection(StringaConnessione)
        Dim Comando As New OleDbCommand(sql, Connessione)
        Dim Reader As OleDbDataReader

        Connessione.Open()
        Reader = Comando.ExecuteReader()
        Me.provincie.DataSource = Reader
        Me.provincie.DataBind()

        Me.provincie.Items.Insert(0, New ListItem("Testo", "valore"))

        Connessione.Close()

    End Sub

    Private Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
        Me.Label1.Text = "Hai scelto: Provincia = " & Me.provincie.SelectedItem.Text & ", ID = " & Me.provincie.SelectedItem.Value
    End Sub

    Private Sub provincie_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles provincie.Init
        CType(sender, DropDownList).Attributes.Add("onchange", "return provincie_onchange();")
    End Sub
End Class