我有这个GridView
使用自定义数据源:
<asp:ScriptManager ID="DateManager" runat="server" />
<asp:UpdatePanel ID="setDate" runat="server"
UpdateMode="Conditional"
ChildrenAsTriggers="true">
<ContentTemplate>
<asp:GridView ID="res" runat="server"
AutoGenerateColumns="False"
CellPadding="4"
ForeColor="#333333"
GridLines="None"
Width="600px"
AllowPaging="True">
<AlternatingRowStyle BackColor="White" />
<Columns>
<asp:BoundField DataField="Ty" HeaderText="Type" />
<asp:BoundField DataField="time" HeaderText="Time" />
<asp:BoundField DataField="duration" HeaderText="Duration" />
<asp:BoundField DataField="confirmed" HeaderText="Status" />
<asp:CommandField SelectText="SelectIt" ShowSelectButton="True" />
</Columns>
<EditRowStyle BackColor="#2461BF" />
<FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
<HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
<PagerStyle BackColor="#2461BF" ForeColor="White" HorizontalAlign="Center" />
<RowStyle BackColor="#EFF3FB" />
<SelectedRowStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333" />
<SortedAscendingCellStyle BackColor="#F5F7FB" />
<SortedAscendingHeaderStyle BackColor="#6D95E1" />
<SortedDescendingCellStyle BackColor="#E9EBEF" />
<SortedDescendingHeaderStyle BackColor="#4870BE" />
</asp:GridView>
</ContentTemplate>
</asp:UpdatePanel>
如何启用多项选择?