WebForm:
dropPostalLineNo.DataSource = "数据源";
dropPostalLineNo.DataTextField = ""; //文本
dropPostalLineNo.DataValueField = ""; //id
dropPostalLineNo.DataBind();
dropPostalLineNo.Items.Insert(0,(new ListItem("全部", "0"))); //添加全部行
WINFORM:
DataTable db = "数据源";
DataRow row = db.NewRow();
row["id"] = "0";
row["Name"] = "name";
db.Rows.InsertAt(row, 0);