/*语法*/

lag(exp_str,offset,defval) over()

Lead(exp_str,offset,defval) over()

--exp_str要取的列

--offset取偏移后的第几行数据

--defval:没有符合条件的默认值 

with x0 as

(select '1'as aa ,to_date('2018-01-01','yyyy-mm-dd') as 日期 from dual

union all

select '2' as aa,to_date('2018-01-15','yyyy-mm-dd') as 日期 from dual

union all

select '3' as aa, to_date('2018-01-26','yyyy-mm-dd') as 日期 from dual )

select aa ,日期,

lead(日期,1,null) over (order by 日期),

lag(日期) over (order by 日期)

 from x0