下拉框怎样绑定树形结构数据呢? 求一个自定义控件DropDownList

[写个昵称都这么麻烦]

求高手给一个自定义控件
数据库表
Id Name Parent
1 新鲜蔬菜 null
1 新鲜水果 null
1 鲜活水产品 null
1 活的禽畜 null
1 白菜类 1
1 蔬菜 1

其中Parent是外键

[写个昵称都这么麻烦]

自己解决了、擦

private void BindDrpClass() {
IList<Cargos.CargoCategory> car = Global.CargoCategoryManager.Get();
DataTable dt = new DataTable();
dt.Columns.Add("Id", typeof(int));
dt.Columns.Add("Name", typeof(string));
dt.Columns.Add("Parent", typeof(int));
dt.Columns.Add("Description", typeof(string));
foreach (Cargos.CargoCategory c in car) {
dt.Rows.Add(new object[] { c.Id, c.Name,
c.Parent==null?0:c.Parent.Id, c.Description });
}
DropDownList1.Items.Clear();
//DropDownList1.Items.Add(new ListItem("作为根", "0"));
//DataRow[] drs = dt.Select("Parent= "+dt.Rows[0][2]);
for (int i = 0; i < dt.Rows.Count; i++) {
if (Convert.ToInt32(dt.Rows[i][2]) == 0) {
string classid = dt.Rows[i][0].ToString();
string classname = dt.Rows[i][1].ToString();
//顶级分类显示形式
classname = "├" + classname;
DropDownList1.Items.Add(new ListItem(classname, classid));
int sonparentid = int.Parse(classid);
string blank = " ├──";
//递归子分类方法
BindDrpNode(sonparentid, dt, blank);
}
DropDownList1.DataBind();
}
}
private void BindDrpNode(int parentid, DataTable dt, string blank) {
for (int i = 0; i < dt.Rows.Count; i++) {
if (Convert.ToInt32(dt.Rows[i][2]) == parentid) {
string classid = dt.Rows[i][0].ToString();
string classname = dt.Rows[i][1].ToString();
classname = blank + classname;
DropDownList1.Items.Add(new ListItem(classname, classid));
int sonparentid = int.Parse(classid);
string blank2 = " " + blank + "──";
BindDrpNode(sonparentid, dt, blank2);
}
}
}

[写个昵称都这么麻烦]

 private void BindDrpClass() {
            IList<Cargos.CargoCategory> car = Global.CargoCategoryManager.Get();
            DataTable dt = new DataTable();
            dt.Columns.Add("Id", typeof(int));
            dt.Columns.Add("Name", typeof(string));
            dt.Columns.Add("Parent", typeof(int));
            dt.Columns.Add("Description", typeof(string));
            foreach (Cargos.CargoCategory c in car) {
                dt.Rows.Add(new object[] { c.Id, c.Name,
                    c.Parent==null?0:c.Parent.Id, c.Description });
            }
            DropDownList1.Items.Clear();
            //DropDownList1.Items.Add(new ListItem("作为根", "0"));
            //DataRow[] drs = dt.Select("Parent= "+dt.Rows[0][2]);
            for (int i = 0; i < dt.Rows.Count; i++) {
                if (Convert.ToInt32(dt.Rows[i][2]) == 0) {
                    string classid = dt.Rows[i][0].ToString();
                    string classname = dt.Rows[i][1].ToString();
                    //顶级分类显示形式
                    classname = "├" + classname;
                    DropDownList1.Items.Add(new ListItem(classname, classid));
                    int sonparentid = int.Parse(classid);
                    string blank = "    ├──";
                    //递归子分类方法
                    BindDrpNode(sonparentid, dt, blank);
                }
                DropDownList1.DataBind();
            }
        }
        private void BindDrpNode(int parentid, DataTable dt, string blank) {
            for (int i = 0; i < dt.Rows.Count; i++) {
                if (Convert.ToInt32(dt.Rows[i][2]) == parentid) {
                    string classid = dt.Rows[i][0].ToString();
                    string classname = dt.Rows[i][1].ToString();
                    classname = blank + classname;
                    DropDownList1.Items.Add(new ListItem(classname, classid));
                    int sonparentid = int.Parse(classid);
                    string blank2 = "        " + blank + "──";
                    BindDrpNode(sonparentid, dt, blank2);
                }
            }
        }