oracle常用函数：TO_DATE

Convert A String With Default Format To A Date	TO_DATE() RETURN DATE
	SELECT TO_DATE('01-JAN-2004') FROM dual;
Convert A String With A Non-Default Format To A Date	TO_DATE(, )
	SELECT TO_DATE('01/01/2004', 'MM/DD/YYYY') FROM dual;
Convert A String With A Non-Default Format And Specify The Language	TO_DATE(, ) RETURN DATE
	SELECT TO_DATE('January 12, 2005, 11:03 A.M.', 'MONTH DD, YYYY, HH:MI A.M.', 'NLS_DATE_LANGUAGE = American') FROM dual;
Convert A String With A Non-Default Format And Specify The Language	TO_DATE(, , ) RETURN DATE
	ALTER SESSION SET NLS_TERRITORY = 'JAPAN'; SELECT TO_DATE('January 12, 2005, 11:03 A.M.', 'Month dd, YYYY, HH:MI A.M.', 'NLS_DATE_LANGUAGE = American') FROM DUAL; ALTER SESSION SET NLS_TERRITORY = 'AMERICA';
Convert A String To 24 Hour Time	TO_DATE(, ) RETURN DATE
	SELECT TO_CHAR(SYSDATE, 'MM/DD/YY HH24:MI:SS') FROM dual;