--上一月

select to_char(trunc(sysdate,'MM')-1,'yyyy-MM-dd') from dual;

--建立函式上週的開始時間

create or replace function fun_acc_getlastweekstart(systemdate in date)   return varchar2 is   result_str varchar2(15); begin   select to_char(trunc(systemdate, 'iw') - 7, 'yyyymmdd')     into result_str     from dual;   return result_str; end fun_acc_getlastweekstart;

--建立函式上週的結束時間

create or replace function fun_acc_getlastweekend(systemdate in date) return varchar2 is   result_str varchar2(15); begin   select to_char(trunc(systemdate, 'iw') - 1, 'yyyymmdd')     into result_str     from dual;   return result_str; end fun_acc_getlastweekend;

--查詢

select  to_date(fun_acc_getlastweekstart(sysdate),'yyyy-MM-dd') from dual;   select to_date(fun_acc_getlastweekend(sysdate),'yyyy-MM-dd') from dual;  

select count(1) from dual  where to_date('2018/10/23','yyyy/MM/dd') between to_date(fun_acc_getlastweekstart(sysdate),'yyyy/MM/dd') and  to_date(fun_acc_getlastweekend(sysdate),'yyyy/MM/dd')

select count(1) from dual  where to_date('2018/10/20','yyyy/MM/dd') between to_date(fun_acc_getlastweekstart(sysdate),'yyyy/MM/dd') and  to_date(fun_acc_getlastweekend(sysdate),'yyyy/MM/dd')