询问有关DataGrid控件的两个问题

<asp:datagrid id="dg" runat="server" Width="460px" Height="175px" DataKeyField="RoleID" AutoGenerateColumns="False" OnUpdateCommand="dg_UpdateCommand" OnCancelCommand="dg_CancelCommand" OnEditCommand="dg_EditCommand" OnDeleteCommand="dg_DeleteCommand">
<Columns>
<asp:BoundColumn DataField="RN" HeaderText="gn"></asp:BoundColumn>
<asp:TemplateColumn HeaderText="addadd">
<ItemTemplate>
<IMG id="Ap" alt="add" style="cursor:hand" onclick="javascript:addper(<%# DataBinder.Eval(Container.DataItem,"ID") %>)" src="images/edit.gif" width="24">
</asp:TextBox>
</ItemTemplate>
</asp:TemplateColumn>
<asp:TemplateColumn HeaderText="am">
<ItemTemplate>
<IMG id="aaa" alt="am" style="cursor:hand" onclick="javascript:addmenu(<%# DataBinder.Eval(Container.DataItem,"ID") %>)" src="images/edit.gif" width="24">
</asp:TextBox>
</ItemTemplate>
</asp:TemplateColumn>
<asp:EditCommandColumn ButtonType="LinkButton" UpdateText="更新" HeaderText="修改" CancelText="取消" EditText="编辑"></asp:EditCommandColumn>
<asp:ButtonColumn Text="删除" HeaderText="删除" CommandName="Delete"></asp:ButtonColumn>
</Columns>
<%# DataBinder.Eval(Container.DataItem,"ID") %> //动态邦定