将时间点的数据变成时间段的数据

--创建测试表
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;

--写法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;

--写法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;