oracle拆分一个连续的字符串

create or replace procedure pc(
  sss out varchar2
)
is
str varchar2(20):='ph,p,cod,do,cu';
en integer:=instr(str,',');
begin
 while en!=0 loop
    dbms_output.put_line(substr(str,0,en-1));
    str:=substr(str,en+1,length(str));
    en:=instr(str,',');
    end loop;
    dbms_output.put_line(substr(str,0,2));
  end;