Question

在Oracle中是否可以进行前导计算？我有一个表，其中第一行设置为100％。此后的每一行等于前一个百分比乘以一个因子，在本示例中为o.99978。我只能得到第一行的答案，而不能一直滚动下去。 seq 3应该等于0.99956，依此类推。

SELECT SEQ, 
(CASE WHEN SEQ = 1 THEN PERC LAG(PERC) OVER (ORDER BY SEQ) * FACTOR END) 
PERC
FROM 
(SELECT 1 SEQ, 0.99978 FACTOR, 1 PERC FROM DUAL UNION ALL
SELECT 2 SEQ, 0.99978 FACTOR, NULL PERC FROM DUAL UNION ALL
SELECT 3 SEQ, 0.99978 FACTOR, NULL PERC FROM DUAL UNION ALL
SELECT 4 SEQ, 0.99978 FACTOR, NULL PERC FROM DUAL UNION ALL
SELECT 5 SEQ, 0.99978 FACTOR, NULL PERC FROM DUAL UNION ALL
SELECT 6 SEQ, 0.99978 FACTOR, NULL PERC FROM DUAL UNION ALL
SELECT 7 SEQ, 0.99978 FACTOR, NULL PERC FROM DUAL UNION ALL
SELECT 8 SEQ, 0.99978 FACTOR, NULL PERC FROM DUAL UNION ALL
SELECT 9 SEQ, 0.99978 FACTOR, NULL PERC FROM DUAL UNION ALL
SELECT 10 SEQ, 0.99978 FACTOR, NULL PERC FROM DUAL);

Answer 1

只需执行以下操作：

select seq, factor, power(factor,seq-1) as perc
from my_table

您的表格就像图片中的表格一样，只有前两列

此处是dbfiddle上的example

Answer 2

Oracle中没有PRODUCT()聚合/分析函数，但是您可以使用EXP(SUM(LN(value)))获得相同的效果（有一些舍入错误），并且要获得累积乘积，可以使用{{ 1}}窗口分析函数。

这演示了如何在每行的值都不相同的情况下执行计算：

SUM( value ) OVER ( ORDER BY ... [RANGE|ROWS] BETWEEN ... )

输出：

SEQ | FACTOR |                                      PERC
--: | -----: | ----------------------------------------:
  1 | .99978 |                                         1
  2 | .99978 | .9997799999999999999999999999999999999907
  3 | .99978 | .9995600483999999999999999999999999999915
  4 | .99978 | .9993401451893519999999999999999999999783
  5 | .99978 | .9991202903574103425599999999999999999725
  6 | .99978 | .9989004838935317122846367999999999999711
  7 |   .999 | .9986807257870751353079341799039999999662
  8 | .99978 | .9976820450612880601726262457240959999696
  9 | .99978 | .9974625550113745767993882679500366988414
 10 | .99978 | .9972431132492720743924924025310876907504

db <>提琴here

Oracle滚动LEAD计算

2 个答案: