procedure TForm1.Button1Click(Sender: TObject);
begin
  Table1.OpenInMemory;   // This will open Table1 in memory.
                         // It is linked with a Memory DB.
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  Table1.Filter   := '( (not Col1 in (1, 2)) and '+
                     '(Col2 <> ''cc'') )  and '+
                     '(Col3 <> ''dd'')'; // AV

//Table1.Filter := '( (not Col1 in (1, 2)) and (Col2 <> ''cc'') )'; // Works
  Table1.Filtered := True;
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
  Table1.Active := False;
end;