SQL> with
  2      closets as
  3          (
  4              select
  5                  rownum n#
  6              from
  7                  dual
  8              connect by
  9                  level <= 6
 10          ),
 11      shelves as
 12          (
 13              select
 14                  rownum n#
 15              from
 16                  dual
 17              connect by
 18                  level <= 4
 19          ),
 20      filled as
 21          (
 22              select
 23                  1 closet,
 24                  1 shelve
 25              from
 26                  dual
 27              union all
 28              select
 29                  2 closet,
 30                  1 shelve
 31              from
 32                  dual
 33              union all
 34              select
 35                  3 closet,
 36                  1 shelve
 37              from
 38                  dual
 39              union all
 40              select
 41                  4 closet,
 42                  1 shelve
 43              from
 44                  dual
 45              union all
 46              select
 47                  5 closet,
 48                  2 shelve
 49              from
 50                  dual
 51          )
 52  select
 53      c.n# "Шкаф",
 54      s.n# "Полка"
 55  from
 56      closets c,
 57      shelves s
 58  minus
 59  select
 60      *
 61  from
 62      filled;

      Шкаф      Полка
---------- ----------
         1          2
         1          3
         1          4
         2          2
         2          3
         2          4
         3          2
         3          3
         3          4
         4          2
         4          3
         4          4
         5          1
         5          3
         5          4
         6          1
         6          2
         6          3
         6          4

19 rows selected