Oracle 11G函数整理(日期函数)

日期函数

1、ADD_MONTHS(date,integer) 给一个日期加上几个月，返回日期

select ADD_MONTHS(sysdate,2)
a1,ADD_MONTHS(sysdate,-2) a2from
dual;

2、CURRENT_DATE 返回当前Session中，当前时区的时间

select current_date from dual;

3、CURRENT_TIMESTAMP返回当前Session中，当前时区的时间戳

select CURRENT_TIMESTAMPfrom dual;

4、DBTIMEZONE 返回数据库时区

select DBTIMEZONE from dual;

5、EXTRACT(year fromexpr)

EXTRACT(month from expr)

EXTRACT(day from expr)

EXTRACT(hour from expr)

EXTRACT(minute from expr)

EXTRACT(second from expr)

EXTRACT(timezone_hour from expr)

EXTRACT(timezone_hour from expr)

EXTRACT(timezone_minute from expr)

EXTRACT(timezone_region from expr)

EXTRACT(timezone_abbr from expr)

select EXTRACT(year from sysdate)
year from dual;
select EXTRACT(month from sysdate)
month from dual;
select EXTRACT(day from sysdate)
day from dual;
select EXTRACT(HOUR from
systimestamp) h
from dual;
select EXTRACT(minute from
systimestamp) m
from dual;
select EXTRACT(second from
systimestamp)ssfrom
dual;
select EXTRACT(timezone_hour from systimestamp)
th from dual;
select EXTRACT(timezone_minute from systimestamp)
tm from dual;
select EXTRACT(timezone_region from systimestamp)
tg from dual;
select EXTRACT(timezone_abbr from systimestamp)
tabbr from dual;

6、FROM_TZ(timaezone_stamp,timezone_value)转换时间戳和时区值为一个带时区的时间戳

SELECT FROM_TZ(TIMESTAMP'2000-03-2808:00:00','3:00')
a1FROM DUAL;

7、LAST_DAY(date) 返回包含当前日期所在月份的最后一天

select LAST_DAY(sysdate)a1,LAST_DAY(ADD_MONTHS(sysdate,2))
a2 from dual;

8、LOCALTIMESTAMP(timestamp_precision)返回当前的日期和时间在会话时区时间戳数据类型的值
SELECT CURRENT_TIMESTAMPa1,LOCALTIMESTAMP a2FROM
DUAL;

9、MONTHS_BETWEEN(date1,date2)返回date1-date2所相差的月份数[可能是小数，按照每月31天计算]

SELECTMONTHS_BETWEEN(TO_DATE('2013-02-15','YYYY-MM-dd'),TO_DATE('2010-12-1','YYYY-MM-dd')
) a1 FROM DUAL;

10、NEW_TIME(date,timezone1,timezone2)计算当时区timezone1中的日期和时间是date时候,返回时区timezone2中的日期和时间

SELECT NEW_TIME(TO_DATE('11-10-201001:23:45','MM-DD-YYYYHH24:MI:SS'),'AST','PST')
a1FROM DUAL;

11、NEXT_DAY(date,ch) 返回时间date的下一个星期几的日期[1-7，星期日表示1]

select NEXT_DAY(sysdate,3)
a1 from dual;

12、NUMTODSINTERVAL(n,interval_unit)
将数字与单位转换为内部时间格式, interval_unit格式有：DAY,HOUR,MINUTE,SECOND 【DS表示 DAY——>SECOND】

select sysdate+NUMTODSINTERVAL(10,'DAY')a1,sysdate+NUMTODSINTERVAL(10,'HOUR') a2,sysdate+NUMTODSINTERVAL(10,'MINUTE')a3,sysdate+NUMTODSINTERVAL(10,'SECOND') a4 from dual

13、NUMTOYMINTERVAL(n, interval_unit) 将数字与单位转换为内部时间格式, interval_unit格式有：YEAR ,MONTH【YM表示 YEAR——>MONTH】

select sysdate+NUMTOYMINTERVAL(10,'YEAR')
a1,sysdate+NUMTOYMINTERVAL(10,'MONTH')a2from
dual

14、ORA_DST_AFFECTED(datetime_expr)

15、ORA_DST_CONVERT(datetime_expr,integer,integer)

16、ORA_DST_ERROR(datetime_expr)

17、ROUND(date,fmt) 日期的四舍五入

SELECT ROUND(sysdate,'YEAR')
a1,ROUND(sysdate,'MONTH')
a2,ROUND(sysdate,'DAY')
a3 FROM DUAL;

18、SESSIONTIMEZONE返回当前session的时区

select SESSIONTIMEZONE a1from
dual;

19、SYS_EXTRACT_UTC(datetime_wuth_timezone) 返回UTC时间

SELECT SYS_EXTRACT_UTC(systimestamp) a1FROM
DUAL;

20、SYSDATE 返回当前时间，数据库驻留的操作系统时间

select SYSDATE a1from
dual;

21、SYSTIMESTAMP 返回系统时间，包含时区信息

select SYSTIMESTAMP a2from
dual;

22、TO_CHAR (datetime,fmt)格式化日期为规定文本

select to_char(SYSTIMESTAMP,'yyyy-MM-ddhh24:mi:ss')
a1 from dual;

23、TO_DSINTERVAL(fmt) 转换一个格式字符串为一个内部的 DAY——>SECOND

select sysdate+TO_DSINTERVAL('10 00:00:00')
a1 from dual;--加10天

select sysdate+TO_DSINTERVAL(to_char(sysdate,'DD
hh24:mi:ss')) a1 from dual;--加上当前时间的时分秒

24、TO_YMINTERVAL(fmt)转换一个格式字符串为一个内部的 YEAR——>MONTH

select sysdate+TO_YMINTERVAL('01-03')
a1 from dual;--加15个月
select sysdate+TO_YMINTERVAL(to_char(sysdate,'yyyy-MM'))
a1 from dual;

25、TO_TIMESTAMP(ch,fmt,nlspara)转换日期字符串为时间戳类型

select TO_TIMESTAMP(sysdate) a1from
dual;
select TO_TIMESTAMP('2013-08-1212:11:11','YYYY-MM_DDHH24:MI:SS')
a1 from dual;

26、TO_TIMESTAMP_TZ(ch,fmt,nlspara) 转换日期字符串为带时区的时间戳类型

select TO_TIMESTAMP_TZ(systimestamp) a1from
dual;
SELECT TO_TIMESTAMP_TZ('1999-12-01 11:00:00-8:00','YYYY-MM-DD
HH:MI:SSTZH:TZM') a1 FROM DUAL;

27、TRUNC (date,fmt) 按格式阶段日期

select TRUNC(sysdate,'YEAR')
a1 from dual;--当年的一月一日
select TRUNC(sysdate,'MONTH')
a1 from dual;--当月的第一天
select TRUNC(sysdate,'DAY')
a1 from dual;--当天0时0分0秒

28、TZ_OFFSET(timezone_name),TZ_OFFSET(‘+HH:MI’) ,TZ_OFFSET(‘-HH:MI’), TZ_OFFSET(SESSIONTIMEZONE),TZ_OFFSET(DBTIMEZONE) 返回时区偏移量

select TZ_OFFSET('US/Eastern') a1from
dual;

select TZ_OFFSET('+08:00') a1from
dual;

select TZ_OFFSET(DBTIMEZONE) a1from
dual;