SQL> WITH test AS (SELECT 1 cc_code, 'asset' cc_desc, NULL cc_class_code FROM DUAL
  2                UNION
  3                SELECT 2, 'current asset', 1 FROM DUAL
  4                UNION
  5                SELECT 3, 'accounts receivable', 2 FROM DUAL
  6                UNION
  7                SELECT 4, 'other current asset', 2 FROM DUAL
  8                UNION
  9                SELECT 5, 'fixed asset', 1 FROM DUAL
 10                UNION
 11                SELECT 6, 'machinery', 5 FROM DUAL
 12                UNION
 13                SELECT 7, 'acc. depr', 6 FROM DUAL
 14                UNION
 15                SELECT 8, 'office eqpt', 5 FROM DUAL),
 16       tree
 17          AS (    SELECT LEVEL lvl,
 18                         cc_code,
 19                         cc_desc
 20                    FROM test
 21              CONNECT BY PRIOR cc_code = cc_class_code
 22              START WITH cc_class_code IS NULL)
 23  SELECT DECODE (lvl, 1, cc_desc) lvl_1,
 24         DECODE (lvl, 2, cc_desc) lvl_2,
 25         DECODE (lvl, 3, cc_desc) lvl_3,
 26         DECODE (lvl, 4, cc_desc) lvl_4
 27    FROM tree;

LVL_1      LVL_2                LVL_3                     LVL_4
---------- -------------------- ------------------------- ---------------
asset
           current asset
                                accounts receivable
                                other current asset
           fixed asset
                                machinery
                                                          acc. depr
                                office eqpt

8 rows selected.

SQL>