SQL> select c1,c2 from pp_test;
 
C1                                                                             C2
-------------------------------------------------------------------------------- --------------------------------------------------------------------------------
a                                                                               d
a                                                                               c
a                                                                               b
b                                                                               c
c                                                                               e
d                                                                               f
e                                                                               g
f                                                                                h
 
8 rows selected
 
SQL> 
SQL> select sys_connect_by_path(c1, '-')
  2    from pp_test
  3   start with c1 = 'a' connect by prior c2 = c1;
 
SYS_CONNECT_BY_PATH(C1,'-')
--------------------------------------------------------------------------------
-a
-a
-a-c
-a-c-e
-a
-a-b
-a-b-c
-a-b-c-e
 
8 rows selected
 
SQL> 

create or replace function ffindmd(c_cf varchar2)
return varchar2
is
   type tb1_cursor_type is ref cursor;
   tb1_cursor tb1_cursor_type;
   amount int:=0;
   v_cf tb1.cf%type;
   res varchar2(500);
   v_temp tb1.cf%type;
begin
   select count(*) into amount from tb1 where cf=c_cf and md<>'a';
   if amount=0 then
      return '';
   else
      open tb1_cursor for select md from tb1 where cf=c_cf and md<>'a';
      dbms_output.put_line('出发点:'||c_cf);
      loop
         fetch tb1_cursor into v_cf;
         exit when tb1_cursor%notfound;
         dbms_output.put_line(c_cf||'的目的：'||v_cf);
         --res:=res||' , '||v_cf;
         v_temp:=ffindmd(v_cf);
         res:=res||v_temp||v_cf;
         --dbms_output.put_line(res);
      end loop;
      close tb1_cursor;
      --dbms_output.put_line(res);
      return res;
   end if;
end ffindmd;


select ffindmd('a') from dual ;

SQL> select distinct 'a' || sys_connect_by_path(p2, '-') from PP_TEXT start with p1 = 'a' connect by
 prior p2 = p1;

'A'||SYS_CONNECT_BY_PATH(P2,'-')
--------------------------------------------------------------------------------
a-b
a-b-c
a-b-c-e
a-b-c-e-g
a-c
a-c-e
a-c-e-g
a-d
a-d-f
a-d-f-h

10行が選択されました。