Oracle取得本月、本年第一天和最后一天

今年第一天 00:00:00

select trunc(sysdate, 'yyyy') from dual;

去年最后一天 23:59:59

select trunc(sysdate,'year')-1+ 0.99999 from dual;

本季第一天 00:00:00

select trunc(sysdate, 'Q') from dual;

本季最后一天 00:00:00

select add_months(trunc(sysdate, 'Q'), 3)-1  from dual;

本季最后一天 23:59:59

select add_months(trunc(sysdate, 'Q'), 3)-0.00001  from dual;

上个月最后一天 23:59:59

select trunc(last_day(add_months(sysdate,-1)))+ 0.99999 from dual;

上个月最后一天 23:45:00

select trunc(last_day(add_months(sysdate,-1)))+ 0.98958 from dual;

上个月第一天 00:00:00

select trunc(add_months(last_day(sysdate), -2) + 1)from dual;

上上个月最后一天 23:59:59

select trunc(last_day(add_months(sysdate,-2)))+ 0.99999 from dual;

本月第一天 00:00:00

select trunc(add_months(last_day(sysdate), -1) + 1)from dual;

select trunc(sysdate, 'mm') from dual;

本周第一天 00:00:00

select trunc(sysdate, 'd') + 1 from dual;

本周最后一天 00:00:00

select trunc(sysdate, 'd') + 7 from dual;

此时此刻

select SYSDATE from dual;

今天 00:00:00

select TRUNC(SYSDATE)   from dual;

昨天 00:00:00

select TRUNC(SYSDATE - 1)   from dual;

昨天23:59:59

select TRUNC(SYSDATE - 1)+0.99999   from dual;

前天 00:00:00

select TRUNC(SYSDATE - 2)   from dual;