用试图能否实现从上月26日到本月25日的月试图？？？？

Question

OK:   select <your column>
   from <yourtable>
   where <yourdatetimecolumn> between 
   to_date('26-'||to_char(ADD_MONTHS(SYSDATE, -1),'MON-YYYY'),'DD-MON-YYYY')
   and
   to_date('25-'||to_char(SYSDATE),'MON-YYYY'),'DD-MON-YYYY')

Answer 1

select count(*) from tab1 a,
(select distinct(to_char(rq,'yyyy-mm')) ny from tab1) b
where a.rq >= to_date(substr(b.ny,1,5)||(to_number(substr(b.ny,6,2))-1)||'-26','yyyy-mm-dd') and a.rq <= to_date(b.ny||'-25','yyyy-mm-dd') 
group by b.ny