SQL> SELECT 1,
  2  level,
  3  job
  4  ,
  5  '',
  6  ename
  7  
  8  
  9  
 10  FROM emp
 11  START WITH mgr IS NULL
 12  CONNECT BY PRIOR empno = mgr
 13  order by level
 14  /
         1      LEVEL JOB       ' ENAME
---------- ---------- --------- - ----------
         1          1 PRESIDENT   KING
         1          2 MANAGER     JONES
         1          2 MANAGER     BLAKE
         1          2 MANAGER     CLARK
         1          3 ANALYST     FORD
         1          3 SALESMAN    WARD
         1          3 CLERK       JAMES
         1          3 CLERK       MILLER
         1          3 SALESMAN    ALLEN
         1          3 ANALYST     SCOTT
         1          3 SALESMAN    MARTIN
         1          3 SALESMAN    TURNER
         1          4 CLERK       ADAMS
         1          4 CLERK       SMITH

SQL> with tab as
  2    (select empno, ename ime, deptno from emp
  3     union
  4     select deptno, dname, null from dept
  5    )
  6  select lpad(' ', 2*level-1) || ime result
  7  from tab
  8  connect by prior empno = deptno
  9  start with deptno is null
 10  order siblings by ime;

RESULT
--------------------
 ACCOUNTING
   CLARK
   KING
   MILLER
 OPERATIONS
 RESEARCH
   ADAMS
   FORD
   JONES
   SCOTT
   SMITH
 SALES
   ALLEN
   BLAKE
   JAMES
   MARTIN
   TURNER
   WARD

18 rows selected.

SQL>

SQL> select decode(grouping(ename),
  2                0, '  '||ename,
  3                job||': '||count(*)||' employees') data
  4  from emp
  5  group by rollup(job, ename)
  6  having grouping(job) = 0
  7  order by job, decode(grouping(ename), 1, ' ', ename)
  8  /
DATA
-------------------------------------------------------------
ANALYST: 2 employees
  FORD
  SCOTT
CLERK: 4 employees
  ADAMS
  JAMES
  MILLER
  SMITH
MANAGER: 3 employees
  BLAKE
  CLARK
  JONES
PRESIDENT: 1 employees
  KING
SALESMAN: 4 employees
  ALLEN
  MARTIN
  TURNER
  WARD