Oracle / Sql查询进行一些计算！

Question

我想提出一个关于oracle / sql查询的问题。

我有一些数据如下，

   Column1
     25
     20
     15
     12
     11
     10

我想得到这样的结果，

   Column1
     5        (25-20)
     5        (20-15)   
     3        (15-12) 
     1        (12-11)
     1        (11-10)

我正在使用游标来获取这些结果。但是，我真的不想使用游标，因为我有很多行要计算。是否有任何函数可以在Oracle / Sql中获得结果，例如“Case When，Roll Up”。

Answer 1

这些函数是lag（）和lead（），请参见此处 - http://www.orafaq.com/node/55

它们可以像这样使用 -

select 
  value - prev_value as diff,
  '(' || to_char(value) || ' - ' || to_char(prev_value) || ')' as expression
from (  
select value, idx, 
  lag(value) over (order by idx) as next_value,
  lead(value) over (order by idx) as prev_value
from(
          select 25 as value, 1 as idx from dual
union all select 20 as value, 2 as idx from dual
union all select 15 as value, 3 as idx from dual
union all select 12 as value, 4 as idx from dual
union all select 11 as value, 5 as idx from dual
union all select 10 as value, 6 as idx from dual
)
) where prev_value is not null