绑定数据
this.ddlgj.DataSource = Web.BLL.NewsMana.Notess().Tables[0];
this.ddlgj.DataTextField = "NewsClassName";
this.ddlgj.DataValueField = "NewsId";
this.ddlgj.DataBind();
Dropdownlist绑定数据后添加,添加第一项
this.ddlgj.Items.Insert(0, new ListItem("--国内外--", "-1"));
清除数据
this.ddllb.Items.Clear();
联动
只需添加onselectedindexchanged事件即可