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和date操作关系最大
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to_date
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具体使用方法:to_date(''2004-11-27'',''yyyy-mm-dd''),前者为
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如;to_date(''2004-11-27 13:34:43'', ''yyyy-mm-dd hh24:mi:ss'') 将得到具体
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多种日期格式:
YYYY: 4位表示
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YYY
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MM:01~12
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MONTH: 9个
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MON: 3位
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WW:
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D:星期中
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DD:月份中
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DDD:年所中
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DAY: 9个
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HH
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HH24:
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MI:
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SS:
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SSSS:从午夜开始过去
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to_char
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SQL> select to_char(sysdate,''yyyy-mm-dd hh24:mi:ss'') time from dual;
TIME
-------------------
2004-10-08 15:22:58
即把当前时间按yyyy-mm-dd hh24:mi:ss格式转换成
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在oracle中处理日期大全
TO_DATE格式
Day:
dd number 12
dy abbreviated fri
day spelled out friday
ddspth spelled out, ordinal twelfth
Month:
mm number 03
mon abbreviated mar
month spelled out march
Year:
yy two digits 98
yyyy four digits 1998
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 ....
[ZT]日期和??函???
1.
日期和
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2.
select to_char( to_date(222,''J''),''Jsp'') from dual
显示Two Hundred Twenty-Two
3.
求某天是星期几
select to_char(to_date(''2002-08-26'',''yyyy-mm-dd''),''day'') from dual;
星期
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select to_char(to_date(''2002-08-26'',''yyyy-mm-dd''),''day'',''NLS_DATE_LANGUAGE = American'') from dual;
monday
设置日期语言
ALTER SESSION SET NLS_DATE_LANGUAGE=''AMERICAN'';
也可以这样
TO_DATE (''2002-08-26'', ''YYYY-mm-dd'', ''NLS_DATE_LANGUAGE = American'')
4.
两个日期间
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select floor(sysdate - to_date(''20020405'',''yyyymmdd'')) from dual;
5. 时间为null
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select id, active_date from table1
UNION
select 1, TO_DATE(null) from dual;
注意要用TO_DATE(null)
6.
a_date between to_date(''20011201'',''yyyymmdd'') and to_date(''20011231'',''yyyymmdd'')
那么12月31号中午12点的后和12月1号
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所以
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7. 日期格式冲突问题
输入
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alter system
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alter session
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或者在to_date中写
select to_char(to_date(''2002-08-26'',''yyyy-mm-dd''),''day'',''NLS_DATE_LANGUAGE = American'') from dual;
注意我这只是举了NLS_DATE_LANGUAGE
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可查看
select * from nls_session_parameters
select * from V$NLS_PARAMETERS
8.
select count(*)
from ( select rownum-1 rnum
from all_objects
where rownum <= to_date(''2002-02-28'',''yyyy-mm-dd'') - to_date(''2002-
02-01'',''yyyy-mm-dd'')+1
)
where to_char( to_date(''2002-02-01'',''yyyy-mm-dd'')+rnum-1, ''D'' )
not
in ( ''1'', ''7'' )
查找2002-02-28至2002-02-01间除星期
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在前后分别
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9.
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
10. Next_day
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Next_day(date, day)
Monday-Sunday, for format code DAY
Mon-Sun, for format code DY
1-7, for format code D
11
select to_char(sysdate,''hh:mi:ss'') TIME from all_objects
注意:第
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可以建立
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create or replace function sys_date
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begin
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end;
select to_char(sys_date,''hh:mi:ss'') from all_objects;
12.
获得小时数
SELECT EXTRACT(HOUR FROM TIMESTAMP ''2001-02-16 2:38:40'') from offer
SQL> select sysdate ,to_char(sysdate,''hh'') from dual;
SYSDATE TO_CHAR(SYSDATE,''HH'')
-------------------- ---------------------
2003-10-13 19:35:21 07
SQL> select sysdate ,to_char(sysdate,''hh24'') from dual;
SYSDATE TO_CHAR(SYSDATE,''HH24'')
-------------------- -----------------------
2003-10-13 19:35:21 19
获取年月日和此类似
13.
年月日
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select older_date,
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years,
months,
abs(
trunc(
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add_months( older_date,years*12+months )
)
) days
from ( select
trunc(months_between(
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mod(trunc(months_between(
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12 ) MONTHS,
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older_date
from ( select hiredate older_date,
add_months(hiredate,rownum)+rownum
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from emp )
)
14.
处理月份天数不定
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select to_char(add_months(last_day(sysdate) +1, -2), ''yyyymmdd''),last_day(sysdate) from dual
16.
找出今年
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select add_months(trunc(sysdate,''year''), 12) - trunc(sysdate,''year'') from dual
闰年
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to_char( last_day( to_date(''02'' || :year,''mmyyyy'') ), ''dd'' )
如果是28就不是闰年
17.
yyyy和rrrr
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''YYYY99 TO_C
------- ----
yyyy 99 0099
rrrr 99 1999
yyyy 01 0001
rrrr 01 2001
18.区别时区
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select to_char( NEW_TIME( sysdate, ''GMT'',''EST''), ''dd/mm/yyyy hh:mi:ss'') ,sysdate
from dual;
19.
5秒钟
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Select TO_DATE(FLOOR(TO_CHAR(sysdate,''SSSSS'')/300) * 300,''SSSSS'') ,TO_CHAR(sysdate,''SSSSS'')
from dual
2002-11-1 9:55:00 35786
SSSSS表示5位秒数
20.
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select TO_CHAR(SYSDATE,''DDD''),sysdate from dual
310 2002-11-6 10:03:51
21.计算小时,分,秒,毫秒
select
Days,
A,
TRUNC(A*24) Hours,
TRUNC(A*24*60 - 60*TRUNC(A*24)) Minutes,
TRUNC(A*24*60*60 - 60*TRUNC(A*24*60)) Seconds,
TRUNC(A*24*60*60*100 - 100*TRUNC(A*24*60*60)) mSeconds
from
(
select
trunc(sysdate) Days,
sysdate - trunc(sysdate) A
from dual
)
select * from tabname
order by decode(mode,''FIFO'',1,-1)*to_char(rq,''yyyymmddhh24miss'');
//
floor((date2-date1) /365) 作为年
floor((date2-date1, 365) /30) 作为月
mod(mod(date2-date1, 365), 30)作为日.
23.next_day
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next_day(sysdate,6)是从当前开始下
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1 2 3 4 5 6 7
日
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oracle中有很多有关日期
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在oracle中有很多有关日期
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1、add_months
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date_value:=add_months(date_value,number_of_months)
例:
SQL> select add_months(sysdate,12) "Next Year" from dual;
Next Year
----------
13-11月-04
SQL> select add_months(sysdate,112) "Last Year" from dual;
Last Year
----------
13-3月 -13
SQL>
2、current_date
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date_value:=current_date
SQL> column sessiontimezone for a15
SQL> select sessiontimezone,current_date from dual;
SESSIONTIMEZONE CURRENT_DA
--------------- ----------
+08:00 13-11月-03
SQL> alter session
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2 /
会话已更改
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SQL> select sessiontimezone,current_timestamp from dual;
SESSIONTIMEZONE CURRENT_TIMESTAMP
--------------- ------------------------------------
-11:00 12-11月-03 04.59.13.668000 下午 -11:
00
SQL>
3、current_timestamp
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timestamp_with_time_zone_value:=current_timestamp([timestamp_precision])
SQL> column sessiontimezone for a15
SQL> column current_timestamp format a36
SQL> select sessiontimezone,current_timestamp from dual;
SESSIONTIMEZONE CURRENT_TIMESTAMP
--------------- ------------------------------------
+08:00 13-11月-03 11.56.28.160000 上午 +08:
00
SQL> alter session
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2 /
会话已更改
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SQL> select sessiontimezone,current_timestamp from dual;
SESSIONTIMEZONE CURRENT_TIMESTAMP
--------------- ------------------------------------
-11:00 12-11月-03 04.58.00.243000 下午 -11:
00
SQL>
4、dbtimezone
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varchar_value:=dbtimezone
SQL> select dbtimezone from dual;
DBTIME
------
-07:00
SQL>
5、extract
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date_value:=extract(date_field from [datetime_value|
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SQL> select extract(month from sysdate) "This Month" from dual;
This Month
----------
11
SQL> select extract(year from add_months(sysdate,36)) "3 Years Out" from dual;
3 Years Out
-----------
2006
SQL>
6、last_day
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date_value:=last_day(date_value)
SQL> select last_day(date''2000-02-01'') "Leap Yr?" from dual;
Leap Yr?
----------
29-2月 -00
SQL> select last_day(sysdate) "Last day of this month" from dual;
Last day o
----------
30-11月-03
SQL>
7、localtimestamp
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timestamp_value:=localtimestamp
SQL> column localtimestamp format a28
SQL> select localtimestamp from dual;
LOCALTIMESTAMP
----------------------------
13-11月-03 12.09.15.433000
下午
SQL> select localtimestamp,current_timestamp from dual;
LOCALTIMESTAMP CURRENT_TIMESTAMP
---------------------------- ------------------------------------
13-11月-03 12.09.31.006000 13-11月-03 12.09.31.006000 下午 +08:
下午 00
SQL> alter session
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会话已更改
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SQL> select localtimestamp,to_char(sysdate,''DD-MM-YYYY HH:MI:SS AM'') "SYSDATE" from dual;
LOCALTIMESTAMP SYSDATE
---------------------------- ------------------------
12-11月-03 05.11.31.259000 13-11-2003 12:11:31 下午
下午
SQL>
8、months_between
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number_value:=months_between(date_value,date_value)
SQL> select months_between(sysdate,date''1971-05-18'') from dual;
MONTHS_BETWEEN(SYSDATE,DATE''1971-05-18'')
----------------------------------------
389.855143
SQL> select months_between(sysdate,date''2001-01-01'') from dual;
MONTHS_BETWEEN(SYSDATE,DATE''2001-01-01'')
----------------------------------------
34.4035409
SQL>
9、next_day
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?周相?日期函?
1.查询某周
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select trunc(decode(ww, 53, to_date(yy || ''3112'', ''yyyyddmm''), to_date(yy || ''-'' || to_char(ww * 7), ''yyyy-ddd'')), ''d'') last_day
from (select substr(''2004-32'', 1, 4) yy, to_number(substr(''2004-32'', 6)) ww
from dual)
select trunc(to_date(substr(''2003-01'',1,5)||to_char((to_number(substr(''2003-01'',6)))*7),''yyyy-ddd''),''d'')-6 first_day from dual
select min(v_date) from
(select (to_date(''200201'',''yyyymm'') + rownum) v_date
from all_tables
where rownum < 370)
where to_char(v_date,''yyyy-iw'') = ''2002-49''
2.查询某周
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select trunc(decode(ww, 53, to_date(yy || ''3112'', ''yyyyddmm''), to_date(yy || ''-'' || to_char(ww * 7), ''yyyy-ddd'')), ''d'') - 6 first_day
from (select substr(''2004-33'', 1, 4) yy, to_number(substr(''2004-33'', 6)) ww
from dual)
select trunc(to_date(substr(''2003-01'',1,5)||to_char((to_number(substr(''2003-01'',6)))*7),''yyyy-ddd''),''d'') last_day from dual
select max(v_date) from
(select (to_date(''200408'',''yyyymm'') + rownum) v_date
from all_tables
where rownum < 370)
where to_char(v_date,''yyyy-iw'') = ''2004-33''
3.查询某周
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select min_date, to_char(min_date,''day'') day from
(select to_date(substr(''2004-33'',1,4)||''001''+rownum-1,''yyyyddd'') min_date
from all_tables
where rownum <= decode(mod(to_number(substr(''2004-33'',1,4)),4),0,366,365)
union
select to_date(substr(''2004-33'',1,4)-1||
decode(mod(to_number(substr(''2004-33'',1,4))-1,4),0,359,358)+rownum,''yyyyddd'') min_date
from all_tables
where rownum <= 7
union
select to_date(substr(''2004-33'',1,4)+1||''001''+rownum-1,''yyyyddd'') min_date
from all_tables
where rownum <= 7
)
where to_char(min_date,''yyyy-iw'') =''2004-33''
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