已知數據如下:
PC E D
工 5 2016-09-01
工 6 2016-09-30
公 5 2016-09-01
公 6 2017-09-30

加入查詢開始日期是2016-09-01，結束日期2016-10-07

希望將上面數據變成:
PC E S N
工 5 2016-09-01 2016-09-30
工 6 2016-09-30 2016-10-07
公 5 2016-09-01 2016-10-07

--創建測試表
create table tmp as 
select ‘工‘ PC, 5 E, to_date(‘2016-09-01‘,‘yyyy-mm-dd‘) D from dual union all
select ‘工‘ PC, 6 E, to_date(‘2016-09-30‘,‘yyyy-mm-dd‘) D from dual union all
select ‘公‘ PC, 5 E, to_date(‘2016-09-01‘,‘yyyy-mm-dd‘) D from dual union all
select ‘公‘ PC, 6 E, to_date(‘2017-09-30‘,‘yyyy-mm-dd
 
‘) D from dual;

--寫法1：
select pc,e,case when to_date(‘2016-09-01‘,‘yyyy-mm-dd‘) >= d then to_date(‘2016-09-01‘,‘yyyy-mm-dd‘) else d end s,
       nvl(lead(d,1)over(partition by pc order by d),to_date(‘2016-10-07‘,‘yyyy-mm-dd‘)) as d from tmp
 where d <= to_date(‘2016-10-07‘,‘yyyy-mm-dd‘)
 order by pc,s;

 
--寫法2： 
select pc,e,d as s,
       nvl(lead(d,1)over(partition by pc order by d),to_date(‘2016-10-07‘,‘yyyy-mm-dd‘)) as n 
  from tmp 
 where d <=to_date(‘2016-10-07‘,‘yyyy-mm-dd‘)
 order by pc,s;

將時間點的數據變成時間段的數據