1.在SQL语句中操作
SELECT [aaa], [bbb] FROM [table] union select -1,'-选择xxx-'
2.在DropDownList的PreRender事件中操作
protected void DropDownList_PreRender(object sender, EventArgs e)
{
if (!IsPostBack)
{
TextBoxKind.Items.Insert(0, new ListItem("-选择xxx-", "0"));
}
}
![](http://www.nextsoft.cn/images/nextsoft-ligth.png)