写出函数如何将123456789实现转置输出0987654321

create or replace function reverse_string(v_strings in varchar2) return varchar2 is
r varchar2(30):='';
va varchar2(30):='';
begin
  for i in 1..length(v_strings) loop
    va:=substr(v_strings,length(v_strings)+1-i,1);
    r:=r||va;
    end loop;
    return r;
end;

 

declare
  v varchar2(30):='';
begin
  v:=reverse_string('1234567890');
  dbms_output.put_line(v);
end;