代码:

sys@EMREP> create table test(a varchar2(10), a varchar2(10));

create table test(a varchar2(10), a varchar2(10))
                                  *
ERROR at line 1:
ORA-00957: duplicate column name
sys@EMREP> create table test("a" varchar2(10), a varchar2(10));

Table created.

sys@EMREP> SELECT table_name, column_name FROM user_tab_cols WHERE table_name = 'TEST';

TABLE_NAME                     COLUMN_NAME
------------------------------ ------------------------------
TEST                           a
TEST                           A
sys@EMREP> insert into test values ('1','1');

1 row created.

sys@EMREP> commit;

Commit complete.

sys@EMREP> select * from test;

a          A
---------- ----------
1          1
  以大写方式存在数据字典中，验证一下：
sys@EMREP> create table test_xxxx(a varchar2(1), "A" varchar2(1));
create table test_xxxx(a varchar2(1), "A" varchar2(1))
                                      *
ERROR at line 1:
ORA-00957: duplicate column name

代码:

sys@EMREP> select to_char(sysdate, 'hh24"小时"mi"分"ss"秒"') AS RESULT from dual;

RESULT
------------------
17小时31分30秒

代码:

sys@EMREP> select 'hh24"小时""mi"分"""ss"秒"' AS RESULT from dual;

RESULT
-----------------------------
hh24"小时""mi"分"""ss"秒"

代码:

select 'alter system kill session ''''|| sid||','||serial#|| '''';' from v$session