无刷新页面更新数据控件的问题

Question

本人对Ajax相对不会很熟悉，我要做一个页面，其中页面有两个控件
dropdownlist1  和  dropdownlist2 
dropdownlist1中的数据来源于代码绑定到数据库中的某一列，dropdownlist2的 数据来源要来自于dropdownlist1的选择值，然后再依据此值绑定出符合条件的数据列，我发现单纯用代码写，页面刷新过于厉害，各位有经验的高手能介绍如何用ASP.NET Ajax 的相关控件进行解决吗？比如 ScriptManager控件UpdatePanel控件 
还有更好、更通用的吗？
顺便能介绍怎么用上面说的这些控件？

Answer 1

UpdatePanel控制多简单啊,网上的例子一大堆,自己搜呗~~

Answer 2

给你个我自己写的 ,炫耀一下,用好了可要回来表扬我呀~~
<div>
            <asp:ScriptManager ID="ScriptManager1" runat="server">
            </asp:ScriptManager>
            <asp:UpdatePanel ID="UpdatePanel1" runat="server">
                <ContentTemplate>
                    <asp:DropDownList ID="DropDownList1" runat="server" DataSourceID="SqlDataSource1"
                        DataTextField="privince" DataValueField="id" Width="142px" AutoPostBack="true"
                        AppendDataBoundItems="true">
                        <asp:ListItem Text="请选择省份" Value="-1"></asp:ListItem>
                    </asp:DropDownList>
                    <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:practise_adConnectionString %>"
                        SelectCommand="SELECT * FROM [user_privince]"></asp:SqlDataSource>
                    <br />
                    
                    <asp:DropDownList ID="DropDownList2" runat="server" DataSourceID="SqlDataSource2"
                        DataTextField="city" DataValueField="id" Width="142px">
                    </asp:DropDownList>
                    <asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:practise_adConnectionString2 %>"
                        SelectCommand="select city,id from user_city where pid=@pid">
                        <SelectParameters>
                            <asp:ControlParameter Name="pid" ControlID="DropDownList1" PropertyName="SelectedValue" />
                        </SelectParameters>
                    </asp:SqlDataSource>
                    &nbsp;
                </ContentTemplate>
                
                <Triggers>
                    <asp:AsyncPostBackTrigger ControlID="DropDownList1" EventName="SelectedIndexChanged" />
                    <asp:AsyncPostBackTrigger ControlID="Button1" EventName="Click" />
                </Triggers>
            </asp:UpdatePanel>
        </div>