oracle获取本周、本月、本季度、本年度的第一天和最后一天(中国的算法)

--本周

select trunc(sysdate,'d')+1 from dual; select trunc(sysdate,'d')+7 from dual;

?

--本月

?

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

?

?

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

??

?

--本年

?

select trunc(sysdate,'yyyy') from dual; select add_months(trunc(sysdate,'yyyy'),12)-1 from dual;

?