procedure TForm1.DBGrid1DrawColumnCell(Sender: TObject; const Rect: TRect;
  DataCol: Integer; Column: TColumn; State: TGridDrawState);
Var
  Str : String;
begin
  if SameText(Column.FieldName, 'Error') then
    begin  
      Str := '';
      if Column.Field.AsString = 'c' then
        Str := 'connection error'
      else
      if Column.Field.AsString = 's' then
        Str := 'success';
      if Str <> '' then
        begin
          DBGrid1.Canvas.TextRect(Rect, Rect.Left 2, Rect.Top 2, Str);
        end;
    end;
end;
方法二：
首先Add All fields 加入所有字段。
然后下下列代码：
procedure TForm1.Query1ErrorGetText(Sender: TField; var Text: String;
  DisplayText: Boolean);
begin
  if Query1Error.value = 'c' then
    text := 'connection error';
  if Query1Error.value = 's' then
    text := 'success'; 
end;