how to show separate digit in delphi 7 dbgrid

function AddPointEvery3Digits(S:String):String;
Var
 L:integer;
begin
 Result:='';
 L:=Length(S);
 While L>3 do
  begin
   Result:='.'+Copy(S,L-2,3)+Result;
   L:=L-3;
   S:=Copy(S,1,L);
  end;
 Result:=S+Result;
end;

add the fields to query --> persistent fields
and set the displayformat in the fields to 0,0

or set at runtime
query.fieldbyname('fieldname').DisplayFormat := '0,0';

only works for numeric fields
and set the
thousandseparator := '.';

in your app

ah, yes it's a DBGrid.

Check this solution :

procedure TForm1.DBGrid1DrawColumnCell(Sender: TObject;
          const Rect: TRect; DataCol: Integer; Column: TColumn; State: TGridDrawState);
var
   st : string;
   sv : variant;
   si : integer;
begin
   with (Sender as TDBGrid), Canvas do
      begin
      if Column.Fieldname = 'my_field_name'  then
         begin
         sv := Column.Field.Value;
         if not (VarIsNull(sv)) then
            begin
            sq := Column.Field.Value;
            if sq < 0 then sq := sq * -1;
            if (sq = 0) or (sq < 0.01) then
               begin
               FillRect(Rect);
               Exit;
            end;
            st := FormatFloat('###.###.###,##;;-', Column.Field.Value);
            if st[1] = ',' then  st := '0' + st
            else  if pos('-,', st) > 0 then  st := '-0' + copy(st,2,10);
            si := round(((Rect.Right - Rect.Left) / 2)) - round(TextWidth(st) / 2);
            TextRect(Rect, Rect.Left + si, Rect.Top+2, st);
         end;  
      end;      
      DefaultDrawColumnCell(Rect, DataCol, Column, State);
   end;  
end;

Oops, Exit missing after line "TextRect........."