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  TO_DATE¸ñʽ  
Day:  
dd number 12  
dy abbreviated fri  
day spelled out friday  
ddspth spelled out, ordinal twelfth  
Month:  
mm number 03  
mon abbreviated mar  
month spelled out march  
Year:  
yy two digits 98  
yyyy four digits 1998  
24Сʱ¸ñʽÏÂʱ¼ä·¶Î§Îª£º 0:00:00 - 23:59:59....  
12Сʱ¸ñʽÏÂʱ¼ä·¶Î§Îª£º 1:00:00 - 12:59:59 ....  
1.  
ÈÕÆÚºÍ×Ö·ûת»»º¯ÊýÓ÷¨£¨to_date,to_char£©  
2.  
select to_char( to_date(222,'J'),'Jsp') from dual  
ÏÔʾTwo Hundred Twenty-Two  
3.  
ÇóijÌìÊÇÐÇÆÚ¼¸  
select to_char(to_date('2002-08-26','yyyy-mm-dd'),'day') from dual;  
ÐÇÆÚÒ»  
select to_char(to_date('2002-08-26','yyyy-mm-dd'),'day','NLS_DATE_LANGUAGE = American') from dual;  
monday  
ÉèÖÃÈÕÆÚÓïÑÔ  
ALTER SESSION SET NLS_DATE_LANGUAGE='AMERICAN';  
Ò²¿ÉÒÔÕâÑù  
TO_DATE ('2002-08-26', 'YYYY-mm-dd', 'NLS_DATE_LANGUAGE = American')  
4.  
Á½¸öÈÕÆÚ¼äµÄÌìÊý  
select floor(sysdate - to_date('20020405','yyyymmdd')) from dual;  
5. ʱ¼äΪnullµÄÓ÷¨  
select id, active_date from table1  
UNION  
select 1, TO_DATE(null) from dual;  
×¢ÒâÒªÓÃTO_DATE(null)  
6.  
a_date between to_date('20011201','yyyymmdd') and to_date('20011231','yyyymmdd')  
ÄÇô12ÔÂ31ºÅÖÐÎç12µãÖ®ºóºÍ12ÔÂ1ºÅµÄ12µã֮ǰÊDz»°üº¬ÔÚÕâ¸ö·¶Î§Ö®Äڵġ£  
ËùÒÔ£¬µ±Ê±¼äÐèÒª¾«È·µÄʱºò£¬¾õµÃto_char»¹ÊDZØÒªµÄ  
7. ÈÕÆÚ¸ñʽ³åÍ»ÎÊÌâ  
ÊäÈëµÄ¸ñʽҪ¿´Äã°²×°µÄORACLE×Ö·û¼¯µÄÀàÐÍ, ±ÈÈç: US7ASCII, date¸ñʽµÄÀàÐ;ÍÊÇ: '01-Jan-01'  
alter system set NLS_DATE_LANGUAGE = American  
alter session set NLS_DATE_LANGUAGE