DropDownList在gridview asp.net C＃中的第二次尝试时刷新

Question

I am facing a problem while adding new records by selecting drop down items. Basically it is a gridview in which I select AddressType, Country then City then CityArea and so on using dropdown. In first attempt it is working fine, but on second attempt when I select Country it reset the selected item.

http://i.stack.imgur.com/GoTtU.jpg

as you can see in the above picture, on second attempt I am going to select Country. As soon as I select the Country it refresh. Look in the below picture:

http://i.stack.imgur.com/ObeT5.jpg

Please help me to find the solution. Thanks.

Here is my code:

<asp:TemplateField HeaderText="Country" HeaderStyle-Width="14%">
                        <ItemTemplate>
                            <asp:Label ID="lblCountry" Text='<%# DataBinder.Eval(Container, "DataItem.Country.Description") %>'
                                runat="server">   </asp:Label>
                        </ItemTemplate>
                        <FooterTemplate>
                            <asp:UpdatePanel runat="server" ID="UPCountry">
                            <ContentTemplate>
                                <asp:DropDownList ID="ddlCountryNew" DataSourceID="odsCountry" runat="server" OnSelectedIndexChanged="ddlCountryNew_SelectedIndexChanged"
                                    AutoPostBack="true" DataTextField="Description" DataValueField="Id" CssClass="myWidth-7" />
                            </ContentTemplate>
                            <Triggers>
                                <asp:AsyncPostBackTrigger ControlID="ddlCountryNew" />
                            </Triggers>
                        </asp:UpdatePanel>
                        </FooterTemplate>
                        <EditItemTemplate>
                            <asp:DropDownList ID="ddlCountry" DataSourceID="odsCountry" runat="server" SelectedValue='<%# DataBinder.Eval(Container, "DataItem.CountryId") %>'
                                DataTextField="Description" DataValueField="Id" CssClass="myWidth-6" ValidationGroup="EditAddressGroup" />
                        </EditItemTemplate>
                    </asp:TemplateField>

C#:

protected void ddlCountryNew_SelectedIndexChanged(object sender, EventArgs e)
    {
        DropDownList ddlCountryNew = (DropDownList)sender;
        hdnCountryId.Value = ddlCountryNew.SelectedItem.Value;
    }

Answer 1

If you want the dropdownlist to trigger Ajax call without refreshing the page

Set EventName="SelectedIndexChanged" like below

<Triggers> 
<asp:AsyncPostBackTrigger ControlID="ddlCountryNew" EventName="SelectedIndexChanged" /> 
</Triggers> 

Have a keen look over through the Update Panel MSDN document with example