SQL> with XXX as
  2  (select CODOGRAMM,
  3           cast(multiset(select regexp_substr(k.CODOGRAMM,
  4                              '[^~]+', 1, rownum)
  5                        from dual
  6                    connect by rownum <= 30) as SYS.Odcivarchar2list) CODES_TBL
  7     from (select 1 ID_RECORD_TYPE, '1~2~3' CODOGRAMM
  8             from DUAL
  9            union all
 10           select 1 ID_RECORD_TYPE, '4~5~6' CODOGRAMM
 11             from DUAL
 12          ) k
 13  )
 14  select  CODOGRAMM, (select max(COLUMN_VALUE) from table(cast(z.CODES_TBL as SYS.Odcivarchar2list))) MAX_vAL
 15    from  XXX z;

CODOG MAX_VAL
----- ----------
1~2~3 3
4~5~6 3

SQL> 2
  2* (select CODOGRAMM,
SQL> c/select /select rownum, /
  2* (select rownum, CODOGRAMM,
SQL> /

CODOG MAX_VAL
----- ----------
1~2~3 3
4~5~6 6

from table(cast(z.CODES_TBL as SYS.Odcivarchar2list))