oracle 累计求和

 //将当前行某列的值与前面所有行的此列值相加,即累计求和:
 //方法一：
 with t as(
      select 1 val from dual union all
      select 3 from dual union all
      select 5 from dual union all
      select 7 from dual union all
      select 9 from dual)
 select val,
        sum(val)
        over (order by rownum rows between unbounded preceding and current row)
        sum_val
 from t
 group by rownum,val
 order by rownum;
        VAL    SUM_VAL
 ---------- ----------
          1          1
          3          4
          5          9
          7         16
          9         25
 //解析：
 //sum(val)计算累积和;
 //order by rownum 按照伪列rownum对查询的记录排序;
 //between unbounded preceding and current row:定义了窗口的起点和终点;
 //unbounded preceding:窗口的起点包括读取到的所有行;
 //current row:窗口的终点是当前行，默认值，可以省略;
 //
 //方法二:
 with cte_1 as(
      select 1 val from dual union all
      select 3 from dual union all
      select 5 from dual union all
      select 7 from dual union all
      select 9 from dual
      )
 ,cte_2 as(
     select rownum rn,val from cte_1
     )
 select a.val , sum(b.val) sum_val
 from cte_2 a , cte_2 b
 where b.rn <= a.rn
 group by a.val
 /
 //方法三：
 //创建一个递归函数，求和
 //f(n) = x + f(n-1)
 create table t
 as
 select 1 id,1 val from dual union all
 select 2,3 from dual union all
 select 3,5 from dual union all
 select 4,7 from dual union all
 select 5,9 from dual
 /
 create or replace function fun_recursion(x in int)
 return integer is
        n integer :=0;
 begin
      select val into n
      from t
      where id=x;
      if x=1 then
         return n;
      else
          return n + fun_recursion(x-1);
      end if;
      exception
      when others then
           dbms_output.put_line(sqlerrm);
 end fun_recursion;
 /
 select val,fun_recursion(id) sum_val from t;
        VAL    SUM_VAL
 ---------- ----------
          1          1
          3          4
          5          9
          7         16
          9         25
 //

 

原帖:http://topic.csdn.net/u/20110503/00/f518c144-5ae4-4843-bf54-056159b6f073.html?3783

关于unbounded preceding,参考:

[1].Order by range unbounded preceding

http://www.java2s.com/Tutorial/Oracle/0320__Analytical-Functions/Orderbyrangeunboundedpreceding.htm

[2].Order by, range unbounded preceding

http://www.java2s.com/Code/Oracle/Select-Query/Orderbyrangeunboundedpreceding.htm

原文地址：http://blog.csdn.net/bobo12082119/article/details/6386142