获取DropDownList控件的ID

 this.DDLType.DataValueField = "ClassTypeID"; 
ID放这里了 是GUID 我想读出来怎么弄    public void DropDownListBind()
    {
        using (OfficeChannel.OfficeChannelDataContext MyCon = new OfficeChannel.OfficeChannelDataContext(ConfigurationManager.ConnectionStrings["OfficeChannelConnectionString_Web"].ConnectionString))
        {
            var linqTxt = from i in MyCon.Class_Type
                          select new
                          {
                              ClassTypeID = i.classTypeID,
                              ClassType = i.classType,
                          };
            this.DDLType.DataSource = linqTxt;
            this.DDLType.DataTextField = "ClassType";
            this.DDLType.DataValueField = "ClassTypeID";
            this.DDLType.DataBind();
        }
    }
    protected void DDLType_SelectedIndexChanged(object sender, EventArgs e)
    {
        using (OfficeChannel.OfficeChannelDataContext MyCon = new OfficeChannel.OfficeChannelDataContext(ConfigurationManager.ConnectionStrings["OfficeChannelConnectionString_Web"].ConnectionString))
        {
            Guid newID = new Guid();//获取ID怎么写 我写的是this.DDLType.DataValueField报错了
            var linqTxt = (from i in MyCon.Class
                           from itype in MyCon.Class_Type
                           where i.classTypeID == itype.classTypeID && i.classTypeID== newID
                           select new
                           {
                               PubTime = i.releaseTime,
                               Title = i.classTitle,
                               Author = Convert.ToString(i.Class_Author.authorName),
                               ClassType = itype.classType
                           }).Take(10);
            DataList1.DataSource = linqTxt;
            DataList1.DataBind();
        }
    }