gridview实现下拉框功能

//把编辑列设模板列,然后dropdownlist绑定数据源
//然后在databinding里把selectedvalue的值绑定到要更新的列名上

       <tr>
            <td><asp:GridView ID="GridView1" runat="server" AutoGenerateColumns=False  DataKeyNames="id"
                        DataSourceID="SqlDataSource1" Width="292px">
                        <Columns>
                            <asp:BoundField DataField="id" HeaderText="id" ReadOnly="True" SortExpression="id" />
                            <asp:TemplateField HeaderText="roles" SortExpression="roles">
                                <EditItemTemplate>
                                    &nbsp;<asp:DropDownList ID="DropDownList1" runat="server" DataSourceID="SqlDataSource1"
                                        DataTextField="power_id" DataValueField="power_id" SelectedValue='<%# Bind("roles") %>'>
                                    </asp:DropDownList><asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:cmssConnectionString %>"
                                        SelectCommand="SELECT [power_id] FROM [power]"></asp:SqlDataSource>
                                </EditItemTemplate>
                                <ItemTemplate>
                                    <asp:Label ID="Label1" runat="server" Text='<%# Bind("roles") %>'></asp:Label>
                                </ItemTemplate>
                            </asp:TemplateField>
                            <asp:CommandField ShowEditButton="True" />
                        </Columns>
                        
                    </asp:GridView>
                </td>
        </tr>
        <tr>
               <td style="width: 73px">
                </td>
                <td style="width: 100px">
                    &nbsp;<asp:SqlDataSource ID="SqlDataSource1" runat="server" UpdateCommand ="update admin set roles=@roles where id=@original_id"  OldValuesParameterFormatString ="original_id" ConnectionString="<%$ ConnectionStrings:cmssConnectionString %>"
                        SelectCommand="SELECT [roles], [id] FROM [admin]"></asp:SqlDataSource>
               </td>
        </tr>