Oracle日期显示格式

SQL> alter session set NLS_DATE_FORMAT='DD-MON-YY';
SQL> select * from test_1;

DW_DATA
------------
07-JAN-01
01-JAN-00
07-JAN-01
12-SEP-14

SQL> select * from test_1 where dw_data='12-SEP-14';

DW_DATA
------------
12-SEP-14


缺省:
SQL> show parameter NLS_DATE_FORMAT

NAME				     TYPE	 VALUE
------------------------------------ ----------- ------------------------------
nls_date_format 		     string	 YYYY-MM-DD

SQL> select * from test_1;

DW_DATA
----------
0001-01-07
0200-01-01
0001-01-07
2014-09-12

SQL> select * from test_1 where dw_data='0001-01-07';

DW_DATA
----------
0001-01-07
0001-01-07

SQL>  select * from test_1 where dw_data='07-JAN-01';

no rows selected

NLS_DATE_FORMAT=YYYY-MM-DD下,就不会返回记录

修改
 alter session set NLS_DATE_FORMAT='DD-MON-YY';
SQL> select * from test_1 where dw_data='07-JAN-01';

no rows selected

SQL> select * from test_1 where dw_data='07-JAN-0001';

DW_DATA
------------
07-JAN-01
07-JAN-01