SQL> run
  1  select *
  2  from dual
  3  where rownum = 1
  4  connect by level = 1
  5  start with level = 1 or rownum = 1
  6  group by cube (dummy)
  7  having grouping(dummy) = 0
  8* order by max(dummy) over (order by dummy)

D
-
X


Execution Plan
----------------------------------------------------------
   0      SELECT STATEMENT Optimizer=CHOOSE
   1    0   SORT (ORDER BY)
   2    1     WINDOW (BUFFER)
   3    2       FILTER
   4    3         SORT (GROUP BY)
   5    4           GENERATE (CUBE)
   6    5             SORT (GROUP BY)
   7    6               COUNT
   8    7                 FILTER
   9    8                   CONNECT BY (WITH FILTERING)
  10    9                     NESTED LOOPS
  11   10                       COUNT
  12   11                         FILTER
  13   12                           TABLE ACCESS (FULL) OF 'DUAL'
  14   10                       TABLE ACCESS (BY USER ROWID) OF 'DUAL'
  15    9                     NESTED LOOPS
  16   15                       BUFFER (SORT)
  17   16                         CONNECT BY PUMP
  18   15                       FILTER
  19   18                         TABLE ACCESS (FULL) OF 'DUAL'