create function F_XYZ(src bigint default 0)
returns varchar(5)
as
declare variable result varchar(5);
begin

  result = ascii_char(ascii_val('A') + src / 456976);
  src = mod(src, 456976);

  result = result || ascii_char(ascii_val('A') + src / 17576);
  src = mod(src, 17576);

  result = result || ascii_char(ascii_val('A') + src / 676);
  src = mod(src, 676);

  result = result || ascii_char(ascii_val('A') + src / 26);
  src = mod(src, 26);

  result = result || ascii_char(ascii_val('A') + src);

  return result;

end