1.oracle中当前系统时间加减用法

select add_months(sysdate, 12) "NEW YEAR" from dual; /**系统时间+12个月后的时间**/

select extract(month from sysdate) "This Month" from dual; /**获取系统时间所在月份**/

select (sysdate + 1) "NEW DATE" from dual; /**系统时间+1天后的时间**/

2.下面一日期处理函数为网上看到一并写在这里

create or replace function DATEADD(datepart varchar2,

num number,

indate date) return date is

Result date;

v_sql varchar2(1000);

v_datepart varchar2(30);

v_ms varchar2(13);

begin

v_datepart := lower(datepart);

/*

Datepart Abbreviations

year yy, y

quarter qq, q

month mm, m

day dd, d

week wk, w

hour hh, h

minute mi, n

second ss, s

millisecond ms

*/

case

when v_datepart in ('year', 'yy', 'y') then

v_sql := 'select :1 + interval ''' || num || ''' year from dual';

when v_datepart in ('quarter', 'qq', 'q') then

v_sql := 'select :1 + (interval ''3'' month) * ' || num ||

' from dual';

when v_datepart in ('month', 'mm', 'm') then

v_sql := 'select :1 + interval ''' || num || ''' month from dual';

when v_datepart in ('week', 'wk', 'w') then

v_sql := 'select :1 + (interval ''7'' day) * ' || num || ' from dual';

when v_datepart in ('day', 'dd', 'd') then

v_sql := 'select :1 + interval ''' || num || ''' day from dual';

when v_datepart in ('hour', 'hh') then

v_sql := 'select :1 + interval ''' || num || ''' hour from dual';

when v_datepart in ('minute', 'mi', 'n') then

v_sql := 'select :1 + interval ''' || num || ''' minute from dual';

when v_datepart in ('second', 'ss', 's') then

v_sql := 'select :1 + interval ''' || num || ''' second from dual';

when v_datepart in ('millisecond', 'ms') then

v_ms := to_char(num / 1000, 'fm999999990.000');

v_sql := 'select :1 + interval ''' || v_ms ||

''' second(9,3) from dual';

else

RAISE_APPLICATION_ERROR(-20001,

'''' || datepart ||

''' is not a recognized dateadd option.');

end case;

execute immediate v_sql

into Result

using indate;

return(Result);

EXCEPTION

WHEN OTHERS THEN

RAISE;

end DATEADD;