extract(year from sysdate) year

,extract(month from sysdate) month

,extract(day from sysdate) day
,extract (hour from sysdate) hour
,extract (minute from sysdate) minute
,extract (second from sysdate) second

select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') as nowTime from dual;   //日期转化为字符串

select to_char(sysdate,'yyyy') as nowYear   from dual;   //获取时间的年

select to_char(sysdate,'mm')    as nowMonth from dual;   //获取时间的月

select to_char(sysdate,'dd')    as nowDay    from dual;   //获取时间的日

select to_char(sysdate,'hh24') as nowHour   from dual;   //获取时间的时

select to_char(sysdate,'mi')    as nowMinute from dual;   //获取时间的分

select to_char(sysdate,'ss')    as nowSecond from dual;   //获取时间的秒