如何获取dropdownlist的值_mycat 数据库绑定

public DataTableReader SelectDept()
        {
            DataTableReader dr = null;
            try
            {
                RunSQL("select * from dept",out dr);
            }
            catch(Exception ex)
            {
                throw new Exception(ex.Message, ex);
            }
            return (dr);
        }

DropDownList2.DataSource = dep.SelectDept();//绑定到数据库中，这样可以动态修改教研室
        DropDownList2.DataTextField = "dep";
        DropDownList2.DataValueField = "id";
        DropDownList2.DataBind();