Update All Values In Gridview Column

[Motorui]

    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataSourceID="SqlDsResLc">
        <Columns>
            <asp:CommandField ShowEditButton="True" />
            <asp:BoundField DataField="Pergunta" HeaderText="Pergunta" SortExpression="Pergunta" />
            <asp:TemplateField HeaderText="Res" SortExpression="Res">
                <EditItemTemplate>
                    <asp:DropDownList ID="DropDownList1" runat="server">
                        <asp:ListItem Value="1">YES</asp:ListItem>
                        <asp:ListItem Value="2">NO</asp:ListItem>
                        <asp:ListItem Value="3">N/A</asp:ListItem>
                        <asp:ListItem></asp:ListItem>
                    </asp:DropDownList>
                </EditItemTemplate>
                <ItemTemplate>
                    <asp:Label ID="Label1" runat="server" Text='<%# Bind("Res") %>'></asp:Label>
                </ItemTemplate>
            </asp:TemplateField>
        </Columns>
    </asp:GridView>