var
tt:TIntegerField;
procedure TForm1.Button1Click(Sender: TObject);
begin
tt:=TIntegerField.Create(self);
tt.FieldName := 'Test1' ;
tt.FieldKind:=fkCalculated;
tt.DataSet:=table1;
table1.active:=true;
end
procedure TForm1.Button2Click(Sender: TObject);
begin
table1.active:=false;
table1.fields.remove(tt);
table1.open;
end