DropDownList数据绑定及添加默认项的问题

string strwhere = " and FID=0 and levels=1 and isshow=0 and channelid=1 and chnname='资讯'";

TypesCollection typelist = TypesDBManager.GetList(strwhere,0,0,out rowcount);

if (typelist != null)

{

TypesEntity te = new TypesEntity();

te.names = "请选择类别";

te.TypesID = 0;

typelist.Insert(0, te);

}

DropDownList1.DataTextField = "names";

DropDownList1.DataValueField = "TypesID";

DropDownList1.DataSource = typelist;

DropDownList1.DataBind();

//ListItem li = new ListItem("请选择类别", "0");

//DropDownList1.Items.Insert(-1, li);

// DropDownList1.Items.FindByValue("0").Selected = true;

//li.Text = "请选择类别";

//li.Value = "1";

//li.Selected = true;

//DropDownList1.Items.Add(li);

//DropDownList1.SelectedValue = "0";

//以上绿色部分 添加默认选项是不行的

原因：首先因DropDownList控件进行绑定时。。其索引为[0]该项已存在，

再在控件中DropDownList1.Items.Add(li); li中的索引0会导致冲突。