Oracle时间日期操作sysdate+(5/24/60/60) 在系统时间基础上延迟5秒sysdate+5/24/60 在系统时间基础上延迟5分钟sysdate+5/24 在系统时间基础上延迟5小时sysdate+5 在系统时间基础上延迟5天add_months(sysdate,-5) 在系统时间基础上延迟5月add_months(sysdate,-5*12) 在系统时间基础上延迟5年上月末的日期：select last_day(add_months(sysdate, -1)) from dual;本月的最后一秒：select trunc(add_months(sysdate,1),'MM') - 1/24/60/60 from dual本周星期一的日期：select trunc(sysdate,'day')+1 from dual年初至今的天数：select ceil(sysdate - trunc(sysdate, 'year')) from dual;今天是今年的第几周:select to_char(sysdate,'fmww') from dual今天是本月的第几周:SELECT TO_CHAR(SYSDATE,'WW') - TO_CHAR(TRUNC(SYSDATE,'MM'),'WW') + 1 AS "weekOfMon" FROM dual本月的天数SELECT to_char(last_day(SYSDATE),'dd') days FROM dual今年的天数select add_months(trunc(sysdate,'year'), 12) - trunc(sysdate,'year') from dual下个星期一的日期SELECT Next_day(SYSDATE,'monday') FROM dual＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝--计算工作日方法create table t(s date,e date);alter session set nls_date_format = 'yyyy-mm-dd';insert into t values('2003-03-01','2003-03-03');insert into t values('2003-03-02','2003-03-03');insert into t values('2003-03-07','2003-03-08');insert into t values('2003-03-07','2003-03-09');insert into t values('2003-03-05','2003-03-07');insert into t values('2003-02-01','2003-03-31');-- 这里假定日期都是不带时间的，否则在所有日期前加trunc即可。

select s,e,e-s+1 total_days,trunc((e-s+1)/7)*5 + length(replace(substr('01111100111110',to_char(s,'d'),mod(e-s+1,7)),'0','')) work_daysfrom t;-- drop table t;引此：/showthread.php?s=1635506cd5f48b1bc3adbe4cde96f227&threadid=1040 60&perpage=15&pagenumber=1=============================================================================== =判断当前时间是上午下午还是晚上SELECT CASEWHEN to_number(to_char(SYSDATE,'hh24')) BETWEEN 6 AND 11 THEN '上午'WHEN to_number(to_char(SYSDATE,'hh24')) BETWEEN 11 AND 17 THEN '下午'WHEN to_number(to_char(SYSDATE,'hh24')) BETWEEN 17 AND 21 THEN '晚上'ENDFROM dual;=============================================================================== =Oracle 中的一些处理日期将数字转换为任意时间格式.如秒:需要转换为天/小时SELECT to_char(floor(TRUNC(936000/(60*60))/24))||'天'||to_char(mod(TRUNC(936000/(60*60)),24))||'小时' FROM DUALTO_DATE格式Day:dd number 12dy abbreviated friday spelled out fridayddspth spelled out, ordinal twelfthMonth:mm number 03mon abbreviated marmonth spelled out marchYear:yy two digits 98yyyy four digits 199824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 ....1.日期和字符转换函数用法（to_date,to_char）2.select to_char( to_date(222,'J'),'Jsp') from dual显示Two Hundred Twenty-Two3.求某天是星期几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')4.两个日期间的天数select floor(sysdate - to_date('20020405','yyyymmdd')) from dual;5. 时间为null的用法select id, active_date from table1UNIONselect 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7. 日期格式冲突问题输入的格式要看你安装的ORACLE字符集的类型, 比如: US7ASCII, date格式的类型就是: '01-Jan-01'alter system set NLS_DATE_LANGUAGE = Americanalter session set NLS_DATE_LANGUAGE = American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，当然还有很多，可查看select * from nls_session_parametersselect * from V$NLS_PARAMETERS8.select count(*)from ( select rownum-1 rnumfrom all_objectswhere rownum <= to_date('2002-02-28','yyyy-mm-dd') - to_date('2002- <br /> 02-01','yyyy-mm-dd')+1)where to_char( to_date('2002-02-01','yyyy-mm-dd')+rnum-1, 'D' )notin ( '1', '7' )查找2002-02-28至2002-02-01间除星期一和七的天数在前后分别调用DBMS_UTILITY.GET_TIME, 让后将结果相减(得到的是1/100秒, 而不是毫秒).9.select months_between(to_date('01-31-1999','MM-DD-YYYY'),to_date('12-31-1998','MM-DD-YYYY')) "MONTHS" FROM DUAL;1select months_between(to_date('02-01-1999','MM-DD-YYYY'),to_date('12-31-1998','MM-DD-YYYY')) "MONTHS" FROM DUAL;1.0322580645161310. Next_day的用法Next_day(date, day)Monday-Sunday, for format code DAYMon-Sun, for format code DY1-7, for format code D11select to_char(sysdate,'hh:mi:ss') TIME from all_objects注意：第一条记录的TIME 与最后一行是一样的可以建立一个函数来处理这个问题create or replace function sys_date return date isbeginreturn sysdate;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 07SQL> select sysdate ,to_char(sysdate,'hh24') from dual;SYSDATE TO_CHAR(SYSDATE,'HH24')-------------------- -----------------------2003-10-13 19:35:21 19获取年月日与此类似13.年月日的处理select older_date,newer_date,years,months,abs(trunc(newer_date-add_months( older_date,years*12+months ))) daysfrom ( selecttrunc(months_between( newer_date, older_date )/12) YEARS,mod(trunc(months_between( newer_date, older_date )),12 ) MONTHS,newer_date,older_datefrom ( select hiredate older_date,add_months(hiredate,rownum)+rownum newer_datefrom emp ))14.处理月份天数不定的办法select to_char(add_months(last_day(sysdate) +1, -2), 'yyyymmdd'),last_day(sysdate) from dual16.找出今年的天数select add_months(trunc(sysdate,'year'), 12) - trunc(sysdate,'year') from dual闰年的处理方法to_char( last_day( to_date('02' ¦ ¦ :year,'mmyyyy') ), 'dd' )如果是28就不是闰年17.yyyy与rrrr的区别'YYYY99 TO_C------- ----yyyy 99 0099rrrr 99 1999yyyy 01 0001rrrr 01 200118.不同时区的处理select to_char( NEW_TIME( sysdate, 'GMT','EST'), 'dd/mm/yyyy hh:mi:ss') ,sysdatefrom dual;19.5秒钟一个间隔Select TO_DATE(FLOOR(TO_CHAR(sysdate,'SSSSS')/300) * 300,'SSSSS') ,TO_CHAR(sysdate,'SSSSS') from dual2002-11-1 9:55:00 35786SSSSS表示5位秒数20.一年的第几天select TO_CHAR(SYSDATE,'DDD'),sysdate from dual310 2002-11-6 10:03:5121.计算小时,分,秒,毫秒selectDays,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)) mSecondsfrom(selecttrunc(sysdate) Days,sysdate - trunc(sysdate) Afrom dual)select * from tabnameorder 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函数next_day(sysdate,6)是从当前开始下一个星期五。