GridView，删除的是索引值而不是主键！
1.前台代码：
<div>
                   <asp:GridView ID="GVZhaoPin" runat="server" AutoGenerateColumns="False" BackColor="White" BorderColor="#CC9966" BorderStyle="None" BorderWidth="1px" CellPadding="4" DataKeyNames="ZhaoPinID" OnLoad="GVZhaoPin_Load" OnRowCancelingEdit="GVZhaoPin_RowCancelingEdit" OnRowCommand="GVZhaoPin_RowCommand" OnRowDataBound="GVZhaoPin_RowDataBound" OnRowDeleting="GVZhaoPin_RowDeleting" OnRowEditing="GVZhaoPin_RowEditing">
                       <Columns>
                           <asp:TemplateField HeaderText="选择">
                               <ItemTemplate>
                                   <asp:CheckBox ID="cbSelect" runat="server" />
                               </ItemTemplate>
                           </asp:TemplateField>
                           <asp:CommandField ButtonType="Button" ShowDeleteButton="True" />
                           <asp:BoundField DataField="ZhaoPinID" />
                           <asp:BoundField DataField="ZhaoPinTitle" HeaderText="标题" />
                           <asp:BoundField DataField="ZhaoPinTime" HeaderText="发布时间">
                           <HeaderStyle HorizontalAlign="Center" />
                           </asp:BoundField>
                           <asp:BoundField HeaderText="发布人" />
                           <asp:CommandField ShowEditButton="True" />
                           <asp:TemplateField>