Oracle 累计求和
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:
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;
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