Oracle中Extract函数的用法

SELECT EXTRACT(YEAR FROM SYSDATE) FROM DUAL; return Current Year
SELECT EXTRACT(MONTH FROM SYSDATE) FROM DUAL; return Current Month
SELECT EXTRACT(DAY FROM SYSDATE) FROM DUAL; return Current Day
SELECT EXTRACT(HOUR FROM TIMESTAMP '2005-10-10 10:10:10') FROM DUAL;
SELECT EXTRACT(MINUTE FROM TIMESTAMP '2005-10-10 10:10:10') FROM DUAL;