oracle中月初月末的表示

当前日期

select to_char(add_months(sysdate,0),'yyyy-MM-dd') day from dual

上月当前日期

select to_char(add_months(sysdate,-1),'yyyy-MM-dd') day from dual 

下月当前日期

select to_char(add_months(sysdate,1),'yyyy-MM-dd') day from dual 

上月首天

select to_char(add_months(last_day(sysdate)+1,-2),'yyyy-MM-dd') day from dual 

上月月末

select to_char(last_day(add_months(last_day(sysdate)+1,-2)),'yyyy-MM-dd') day from dual 

当月首天

select to_char(add_months(last_day(sysdate)+1,-1),'yyyy-MM-dd') day from dual 

当月月末

select to_char(last_day(add_months(last_day(sysdate)+1,-1)),'yyyy-MM-dd') day from dual

下月首天

select to_char(add_months(last_day(sysdate)+1,0),'yyyy-MM-dd') day from dual

下月月末

select to_char(last_day(add_months(last_day(sysdate)+1,0)),'yyyy-MM-dd') day from dual