分类： Oracle
2013-03-08 11:01:36
Oracle日期格式&操作
日期格式：
Year:
yy two digits 两位年 显示值:07
yyy three digits 三位年 显示值:007
yyyy four digits 四位年 显示值:2007
Month:
mm number 两位月 显示值:11
mon abbreviated 字符集表示 显示值:11月,若是英文版,显示nov
month spelled out 字符集表示 显示值:11月,若是英文版,显示november
Day:
dd number 当月第几天 显示值:02
ddd number 当年第几天 显示值:02
dy abbreviated 当周第几天简写 显示值:星期五,若是英文版,显示fri
day spelled out 当周第几天全写 显示值:星期五,若是英文版,显示friday
ddspth spelled out, ordinal twelfth
Hour:
hh two digits 12小时进制 显示值:01
hh24 two digits 24小时进制 显示值:13
Minute:
mi two digits 60进制 显示值:45
Second:
ss two digits 60进制 显示值:25
其它
Q digit 季度 显示值:4
WW digit 当年第几周 显示值:44
W digit 当月第几周 显示值:1
24小时格式下时间范围为： 0:00:00 - 23:59:59....
12小时格式下时间范围为： 1:00:00 - 12:59:59 ....
select sysdate from dual; //2013/1/6 16:12:54
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') as nowTime from dual; //2013-01-06 16:13:48
select to_char(sysdate,'yyyy') as nowYear from dual; //2013
select to_char(sysdate,'mm') as nowMonth from dual; //01
select to_char(sysdate,'dd') as nowDay from dual; //06
select to_char(sysdate,'hh24') as nowHour from dual; //16
select to_char(sysdate,'mi') as nowMinute from dual; //13
select to_char(sysdate,'ss') as nowSecond from dual; //48
select to_date('2004-05-07 13:23:44','yyyy-mm-dd hh24:mi:ss') from dual //2004/5/7 13:23:44
select to_char(to_date('2002-08-26','yyyy-mm-dd'),'day') from dual; //星期一
select to_char(to_date('2002-08-26','yyyy-mm-dd'),'day','NLS_DATE_LANGUAGE = American') from dual; //monday
select floor(sysdate - to_date('20121231','yyyymmdd')) from dual; //6 // 两个日期间的天数
select to_date(null) from dual; //空
between to_date('20011201','yyyymmdd') and to_date('20011231','yyyymmdd') //那么12月31号中午12点之后和12月1号的12点之前是不包含在这个范围之内的。
//所以，当时间需要精确的时候，觉得to_char还是必要的
select months_between(to_date('01-31-1999','MM-DD-YYYY'),to_date('12-31-1998','MM-DD-YYYY')) "MONTHS" FROM DUAL; //1
select months_between(to_date('02-01-1999','MM-DD-YYYY'),to_date('12-31-1998','MM-DD-YYYY')) "MONTHS" FROM DUAL; //1.03225806451613
select next_day(sysdate,'星期一') from dual //2013/1/7 16:32:16
select next_day(sysdate,2) from dual //2013/1/7 16:38:53
select next_day(sysdate,'星期日') from dual //2013/1/13 16:33:05
select next_day(to_date('2013-01-04','yyyy-mm-dd'),'星期二') from dual; //2013/1/8
日期操作：
时间差
select (sysdate-to_date('2007-11-02 15:55:03','yyyy-mm-dd hh24:mi:ss'))/365 from dual; //5.18365449010654
select to_number(sysdate-to_date('2007-11-02 15:55:03','yyyy-mm-dd hh24:mi:ss'))/365 from dual; //5.18365537798072
select floor(to_number(sysdate-to_date('2007-11-02 15:55:03','yyyy-mm-dd hh24:mi:ss'))/365) as spanYears from dual //5 //时间差-年
select ceil(months_between(sysdate,to_date('2007-11-02 15:55:03','yyyy-mm-dd hh24:mi:ss'))) as spanMonths from dual //63 //时间差-月
select floor(to_number(sysdate-to_date('2007-11-02 15:55:03','yyyy-mm-dd hh24:mi:ss'))) as spanDays from dual //时间差-天
select floor(to_number(sysdate-to_date('2007-11-02 15:55:03','yyyy-mm-dd hh24:mi:ss'))*24) as spanHours from dual //时间差-时
select floor(to_number(sysdate-to_date('2007-11-02 15:55:03','yyyy-mm-dd hh24:mi:ss'))*24*60) as spanMinutes from dual //时间差-分
select floor(to_number(sysdate-to_date('2007-11-02 15:55:03','yyyy-mm-dd hh24:mi:ss'))*24*60*60) as spanSeconds from dual //时间差-秒
修改时间
select sysdate from dual; //2013/1/6 17:08:53
加法
select add_months(sysdate,12) from dual; //2014/1/6 17:08:53 --加1年
select add_months(sysdate,1) from dual; //2013/2/6 17:08:53 --加1月
select to_char(sysdate+7,'yyyy-mm-dd HH24:MI:SS') from dual; //2013-01-13 17:08:53 --加1星期
select to_char(sysdate+1,'yyyy-mm-dd HH24:MI:SS') from dual; //2013-01-07 17:08:53 --加1天
select to_char(sysdate+1/24,'yyyy-mm-dd HH24:MI:SS') from dual; //2013-01-06 18:08:53 --加1小时
select to_char(sysdate+1/24/60,'yyyy-mm-dd HH24:MI:SS') from dual; //2013-01-06 17:09:53 --加1分钟
select to_char(sysdate+1/24/60/60,'yyyy-mm-dd HH24:MI:SS') from dual; //2013-01-06 17:08:54 --加1秒
减法
select add_months(sysdate,-12) from dual; //2012/1/6 17:08:53 --减1年
select add_months(sysdate,-1) from dual; //2012/12/6 17:08:53 --减1月
select to_char(sysdate-7,'yyyy-mm-dd HH24:MI:SS') from dual; //2012-12-30 17:08:53 --减1星期
select to_char(sysdate-1,'yyyy-mm-dd HH24:MI:SS') from dual; //2013/1/5 17:08:53 --减1天
select to_char(sysdate-1/24,'yyyy-mm-dd HH24:MI:SS') from dual; //2013/1/6 16:08:53 --减1小时
select to_char(sysdate-1/24/60,'yyyy-mm-dd HH24:MI:SS') from dual; //2013/1/6 17:07:53 --减1分钟
select to_char(sysdate-1/24/60/60,'yyyy-mm-dd HH24:MI:SS') from dual; //2013/1/6 17:08:52 --减1秒 类推至毫秒0.001秒 oracle认证http://www.cuug.com/
