<asp:DropDownList ID="DropDownList1"  runat="server"   DataSourceID="ObjectDataSource1" 
DataTextField="" DataValueField="">
<asp:ObjectDataSource ID="ObjectDataSource1" runat="server">假如ObjectDataSource有3个字段FirstName,LastName,ID.
如何让DataTextField同时绑定FirstName,LastName,DataValueField=ID?