函数remove_constants

create or replace function remove_constants(p_query in varchar2)
  return varchar2 as
  l_query     long;
  l_char      varchar2(1);
  l_in_quotes boolean default false;
begin
  for i in 1 .. length(p_query) loop
    l_char := substr(p_query, i, 1);
    if (l_char = '''' and l_in_quotes) then
      l_in_quotes := false;
    elsif (l_char = '''' and not l_in_quotes) then
      l_in_quotes := true;
      l_query     := l_query || '''#';
    end if;
    if (not l_in_quotes) then
      l_query := l_query || l_char;
    end if;
 
  end loop;
  l_query := translate(l_query, '0123456789', '@@@@@@@@@@@@@@@@@@@@');
  for i in 0 .. 8 loop
    l_query := replace(l_query, lpad('@', 10 - i, '@'), '@');
    l_query := replace(l_query, lpad(' ', 10 - i, ' '), ' ');
  end loop;
  return upper(l_query);
end;