type
 THackAccess = class(TCustomGrid);
{
 THackAccess Is needed because TCustomGrid.MoveColumn is
 protected and you can't access it directly.
}
// In the implementation-Section:
procedure MoveDBGridColumns(DBGrid: TDBGrid; FromColumn, ToColumn: Integer);
begin
 THackAccess(DBGrid).MoveColumn(FromColumn, ToColumn);
end;

{Example}
procedure TForm1.Button1Click(Sender: TObject);
begin
 MoveDBGridColumns(DBGrid1, 1, 2)
end;