Материал из .Net Framework эксперт
Select the value of asp:DropDownList Selected Item
<%@ Page Language="VB" %>
<script runat="server">
Sub DropDownList1_SelectedIndexChanged(sender As Object, e As EventArgs)
Select Case DropDownList1.SelectedItem.Value
Case 0: Label1.Text = String.Empty " Reset the Label1.Text
Case 1: Label1.Text = "You got Grade E!"
Case 2: Label1.Text = "You got Grade D!"
Case 3: Label1.Text = "You got Grade C!"
Case 4: Label1.Text = "You got Grade B!"
Case 5: Label1.Text = "You got Grade A!"
End Select
End Sub
</script>
<html>
<head>
</head>
<body>
<form runat="server">
<p>
<asp:DropDownList id="DropDownList1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
<asp:ListItem Value="0" Selected="True">- Please select a range of score -</asp:ListItem>
<asp:ListItem Value="1">0 - 20</asp:ListItem>
<asp:ListItem Value="2">21 - 40</asp:ListItem>
<asp:ListItem Value="3">40 - 60</asp:ListItem>
<asp:ListItem Value="4">61 - 80</asp:ListItem>
<asp:ListItem Value="5">81 - 100</asp:ListItem>
</asp:DropDownList>
</p>
<p>
<asp:Label id="Label1" runat="server"></asp:Label>
</p>
</form>
</body>
</html>