表结构及记录

object tarea: TFDQuery
    Connection = FDConnection1
    SQL.Strings = (
      'select *'
      'from tArea  order by fParentCode')
    Left = 160
    Top = 240
  end

 object tv: TTreeView
    Left = 0
    Top = 0
    Width = 554
    Height = 320
    Align = alClient
    Indent = 19
    TabOrder = 1
    ExplicitLeft = 40
    ExplicitTop = 32
    ExplicitWidth = 121
    ExplicitHeight = 97
  end

代码

procedure TForm1.FormCreate(Sender: TObject);
  var
    nodes:ttreenodes;
    node:ttreenode ;
    CurItem ,CurItem1:Ttreenode ;
    nodestr:string;
    lastparent,temp:string;
    i,j:integer   ;
begin
         TV.Items.Clear;
     nodes:=TV.Items;
     Tarea.Active:=true;
     node:=nodes.add(nil,Tarea.FieldByName('fCode').Value+'_'+Tarea.FieldByName('fNAME').Value);
     Tarea.Next;
     while NOT Tarea.Eof  do
     BEGIN
          if Tarea.FieldByName('fParentCode').AsString='' then
             nodes.add(nil,Tarea.FieldByName('fCode').Value+'_'+Tarea.FieldByName('fNAME').Value);  //省份

           if Tarea.FieldByName('fParentCode').AsString<>lastparent then
            //当前记录 fParentCode跟上条记录 fParentCode  不相等，表明是换一个父代了
            //需查找
           begin
              CurItem := TV.Items.GetFirstNode;
                while CurItem <> nil do
                   begin
                    if copy( CurItem.Text,1,pos('_',CurItem.Text)-1) =Tarea.FieldByName('fParentCode').Value then
                       begin
                        CurItem.Selected:=true;
                        break;
                        end;
                       CurItem := CurItem.GetNext;
                   end;
              nodes.addCHILD(CurItem,Tarea.FieldByName('fCode').Value+'_'+Tarea.FieldByName('fNAME').Value);  //
           end;

          if (Tarea.FieldByName('fParentCode').AsString<>'')
                              AND
              (Tarea.FieldByName('fParentCode').AsString=lastparent)
              //当前记录 fParentCode跟上条记录 fParentCode  相等，表明是同一个父代了，直接添加就行
              then
              BEGIN
                 nodes.addCHILD(CurItem,Tarea.FieldByName('fCode').Value+'_'+Tarea.FieldByName('fNAME').Value);  //
              END;

           lastparent:= Tarea.FieldByName('fParentCode').AsString;
           Tarea.Next;
     END;
     nodes.GetFirstNode;

end;

end.

效果如下