sql>CREATE TABLE EMP(ENAME VARCHAR2(30));

Table created.

Elapsed: 00:00:00.15
sql>
sql>
sql>INSERT INTO EMP VALUES('JanuAry');

1 row created.

Elapsed: 00:00:00.09
sql>INSERT INTO EMP VALUES('mArcH');

1 row created.

Elapsed: 00:00:00.10
sql>
sql>INSERT INTO EMP VALUES('JulY');

1 row created.

Elapsed: 00:00:00.08


sql>INSERT INTO EMP VALUES('MAY'); 

1 row created.

Elapsed: 00:00:00.08
sql>INSERT INTO EMP VALUES('june');

1 row created.

Elapsed: 00:00:00.08
sql>select * from emp;

ENAME
------------------------------
JanuAry
mArcH
JulY
MAY
june

Elapsed: 00:00:00.17

sql>  select ename from  
    (select REGEXP_SUBSTR (ename, '[^ ]+', 1, level) ename
     from EMP
     connect by level <= length(regexp_replace(ename,'[^ ]*'))+1
    )
 where regexp_instr(ename,'[A-Z]') > 0;  2    3    4    5    6  

ENAME
------------------------------------------------------------------------------------------
JanuAry
mArcH
JulY
MAY

Elapsed: 00:00:00.17
sql>

SQL> col upchar format a10
SQL> with
  2    data as (
  3      select ename, substr(ename,column_value,1) ch, column_value cn
  4      from emp,
  5           table(cast(multiset(select level from dual connect by level <= length(ename))
  6                      as sys.odciNumberList))
  7      where substr(ename,column_value,1)=upper(substr(ename,column_value,1))
  8    )
  9  select ename, listagg(ch) within group (order by cn) upchar
 10  from data
 11  group by ename
 12  order by ename
 13  /
ENAME                          UPCHAR
------------------------------ ----------
JanuAry                        JA
JulY                           JY
MAY                            MAY
mArcH                          AH

SQL> select translate(ename,'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz','ABCDEFGHIJKLMNOPQRSTUVWXYZ') from emp;

TRANSLATE(ENAME,'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ','ABCDEFGH
--------------------------------------------------------------------------------
JA
AH
JY
MAY

with t as (
           select 'JanuAry' month from dual union all
           select 'mArcH' from dual union all
           select 'JulY' from dual union all
           select 'MAY' from dual union all
           select 'june' from dual
          )
select  regexp_replace(month,'[^A-Z]') month
  from  t
  where regexp_replace(month,'[^A-Z]') is not null
/

MONTH
-------
JA
AH
JY
MAY

SQL> 

SQL> column u_str format A10;
SQL> with t as (
  2             select 'JanuAry' str from dual union all
  3             select 'mArcH' from dual union all
  4             select 'JulY' from dual union all
  5             SELECT 'MAY' FROM DUAL UNION ALL
  6             SELECT 'june' FROM DUAL UNION ALL
  7             select 'juneJUNE' from dual
  8            )
  9  SELECT Regexp_replace(str, '[a-z]', '') u_str
 10  FROM   t;

U_STR
----------
JA
AH
JY
MAY

JUNE

6 rows selected.