Hi, i'm giving u a similar soln., just change this according to ur requirements....
Change connection string, query, DataTextField, DataValueField... that's all...
<div>
<asp:UpdatePanel ID="UpdatePanel2" runat="server">
<ContentTemplate>
<asp:DropDownList ID="DropDownList2" runat="server"
DataSourceID="SqlDataSource2" DataTextField="make"
DataValueField="id" AutoPostBack="True">
</asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSource2" runat="server"
ConnectionString="<%$ ConnectionStrings:TestDbConnectionString %>"
SelectCommand="SELECT * FROM [Manufacturer]"></asp:SqlDataSource>
<br />
<asp:DropDownList ID="DropDownList1" runat="server"
DataSourceID="SqlDataSource1" DataTextField="product_name"
DataValueField="product_id">
</asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSource1" runat="server"
ConnectionString="<%$ ConnectionStrings:TestDbConnectionString %>"
SelectCommand="SELECT [product_id], [product_name] FROM [product] WHERE ([mid] = @mid)">
<SelectParameters>
<asp:ControlParameter ControlID="DropDownList2" Name="mid"
PropertyName="SelectedValue" Type="Int32" />
</SelectParameters>
</asp:SqlDataSource>
</ContentTemplate>
</asp:UpdatePanel>
</div>
If u have any clarifications reply to this,...
Mark it if u find this useful...