問題與NLS_DATE_FORMAT

Question

爲什麼我看到下面不同的日期格式：請參見SELECT語句和匿名塊的輸出的輸出

13:46:23 13:46:23 SQL> conn prashant-mishra/ *****@***** 

Connected to Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 

13:47:56 13:47:56 SQL> CREATE TABLE test AS SELECT SYSDATE as test_date 
         FROM dual; 
Table created 


13:48:15 13:48:15 SQL> SELECT test_date FROM test; 
        TEST_DATE 
        ----------- 
        **10/13/2016** 

13:50:17 13:50:17 SQL> BEGIN 
        2 FOR rec IN (SELECT test_date FROM test) LOOP 
        3  dbms_output.put_line(rec.test_date); 
        4 END LOOP; 
        5 END; 
        6/

**13-OCT-16** 
PL/SQL procedure successfully completed 

其他有用的信息可能是：

13:50:20 13:50:20 SQL> SELECT value FROM v$nls_parameters 
         WHERE parameter ='NLS_DATE_FORMAT'; 
      VALUE 
      ---------------------------------------------------------------- 
      DD-MON-RR 


13:50:45 13:50:45 SQL> SELECT SYSDATE FROM dual; 
      SYSDATE 
      ----------- 
      **10/13/2016** 

Answer 1

SQL * Plus使用NLS_DATE_FORMAT將日期格式化爲字符串，因此完整的測試用例需要事先顯示此參數。請您嘗試以下，看看你會得到一致的格式：

SQL> select value from nls_session_parameters where parameter = 'NLS_DATE_FORMAT'; 

VALUE 
---------------------------------------------------------------- 
DD-MON-RR 

SQL> select sysdate from dual; 

SYSDATE 
------------------ 
13-OCT-16 

SQL> alter session set nls_date_format = 'YYYY-MM-DD'; 

Session altered. 

SQL> select sysdate from dual; 

SYSDATE 
---------- 
2016-10-13 

SQL> alter session set nls_date_format = 'DD-MON-RR'; 

Session altered. 

SQL> select sysdate from dual; 

SYSDATE 
------------------ 
13-OCT-16 

SQL> 

您可根據您的意見，下面的輸出：

SQL> select value from nls_session_parameters where parameter = 'NLS_DATE_FORMAT'; 
VALUE 
DD-MON-RR 

SQL> select sysdate from dual; 
SYSDATE 
10/14/2016 

SQL> alter session set nls_date_format = 'YYYY-MM-DD'; 
Session altered 

SQL> select sysdate from dual; 
SYSDATE 
10/14/2016 

SQL> alter session set nls_date_format = 'DD-MON-RR'; 
Session altered 

SQL> select sysdate from dual; 
SYSDATE 
10/14/2016 

所以 - sqlplus存在無視會話NLS_DATE_FORMAT和使用它的唯一本地格式MM/DD/YYYY。我不認爲SQL * Plus中有日期格式覆蓋，但可能是錯誤的。你有沒有在不同的客戶端嘗試相同的命令？