如何根据另一列计算以下 n 行的平均值 - SQL (Oracle) - 先前回答问题的更新版本

Question

我正在尝试按月计算每个 POLICY_ID 的 PREMIUM 平均每月价值，如下图所示。当客户每年 his/her PAYMENT_FREQUENCY 更新为不同于 12 的值时，我需要手动计算 PREMIUM 的平均每月值。此外，平均每月的 PREMIUM 金额可以及时更改。例如，对于POLICY_ID = 1，从“2015/11/01”开始平均每月保费从120增加到240。

如何才能获得名为 MONTHLY _PREMIUM_DESIRED 的列中显示的值？

（此问题的早期版本已回答：）

注：Oracle 版本 12c

我尝试过的：

SELECT 
    T.*,
    SUM(PREMIUM) OVER(PARTITION BY T.POLICY_ID ORDER BY T.POLICY_ID, T.PAYMENT_DATE ROWS BETWEEN CURRENT ROW AND 12/T.YEARLY_PAYMENT_FREQ-1 FOLLOWING ) / (12/T.YEARLY_PAYMENT_FREQ) MONTLY_PREMIUM_CALCULATED
FROM MYTABLE2 T
;

数据代码：

DROP TABLE MYTABLE2;
CREATE TABLE MYTABLE2 (POLICY_ID NUMBER(11), PAYMENT_DATE DATE, PREMIUM NUMBER(5), YEARLY_PAYMENT_FREQ NUMBER(2),MONTHLY_PREMIUM_DESIRED NUMBER(5));
INSERT INTO MYTABLE2 VALUES (1, DATE '2014-10-01',120,12,120);
INSERT INTO MYTABLE2 VALUES (1, DATE  '2014-11-01',360,4,120);
INSERT INTO MYTABLE2 VALUES (1, DATE '2014-12-01',0,4,120);
INSERT INTO MYTABLE2 VALUES (1, DATE '2015-01-01',0,4,120);
INSERT INTO MYTABLE2 VALUES (1, DATE '2015-02-01',360,4,120);
INSERT INTO MYTABLE2 VALUES (1, DATE '2015-03-01',0,4,120);
INSERT INTO MYTABLE2 VALUES (1, DATE '2015-04-01',0,4,120);
INSERT INTO MYTABLE2 VALUES (1, DATE '2015-05-01',720,2,120);
INSERT INTO MYTABLE2 VALUES (1, DATE '2015-06-01',0,2,120);
INSERT INTO MYTABLE2 VALUES (1, DATE '2015-07-01',0,2,120);
INSERT INTO MYTABLE2 VALUES (1, DATE '2015-08-01',0,2,120);
INSERT INTO MYTABLE2 VALUES (1, DATE '2015-09-01',0,2,120);
INSERT INTO MYTABLE2 VALUES (1, DATE '2015-10-01',0,2,120);
INSERT INTO MYTABLE2 VALUES (1, DATE '2015-11-01',240,12,240);
INSERT INTO MYTABLE2 VALUES (1, DATE '2016-12-01',240,12,240); 
INSERT INTO MYTABLE2 VALUES (1, DATE '2016-01-01',960,4,240);     
INSERT INTO MYTABLE2 VALUES (1, DATE '2016-02-01',0,4,240);   
INSERT INTO MYTABLE2 VALUES (1, DATE '2016-03-01',0,4,240);    
INSERT INTO MYTABLE2 VALUES (1, DATE '2016-04-01',0,4,240);  
INSERT INTO MYTABLE2 VALUES (1, DATE '2016-05-01',960,4,240);     
INSERT INTO MYTABLE2 VALUES (1, DATE '2016-06-01',0,4,240);     
INSERT INTO MYTABLE2 VALUES (1, DATE '2016-07-01',0,4,240);      
INSERT INTO MYTABLE2 VALUES (1, DATE '2016-08-01',0,4,240);    
INSERT INTO MYTABLE2 VALUES (2, DATE '2015-01-01',60,3,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2015-02-01',0,3,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2015-03-01',0,3,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2015-04-01',0,3,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2015-05-01',180,1,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2015-06-01',0,1,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2015-07-01',0,1,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2015-08-01',0,1,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2015-09-01',0,1,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2015-10-01',0,1,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2015-11-01',0,1,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2015-12-01',0,1,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2016-01-01',0,1,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2016-02-01',0,1,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2016-03-01',0,1,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2016-04-01',0,1,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2016-05-01',15,12,15);
INSERT INTO MYTABLE2 VALUES (2, DATE '2016-06-01',15,12,15);
SELECT * FROM MYTABLE2;

Answer 1

我想你追求的是这个：

select t.*, 
       last_value(nullif(premium * yearly_payment_freq / 12, 0) ignore nulls) 
                   over (partition by policy_id order by payment_date)
                   as monthly_premium_calculated
from   mytable2 t
;

对于非零付款的月份，这会采用已支付的保费，乘以每年的频率以获得等效的年度保费，并将结果除以 12 以获得每月的等效值。对于保费为零的月份，假设该月的保费是在较早的月份支付的（频率小于 "monthly" - 即，保费支付了整个季度或半年, 或年份).

运行关于你的数据我发现你的 "desired" 数据有误。对于 POLICY_ID = 1，对于 '2016-01-01'，您显示付款为 960，年频率为 4，"desired monthly amount" 为 240。这不是错误吗？ 4的频率表示"quarterly"，如果季度金额为960，则每月金额为320，而不是240。对吗？我的计算得到结果 320.

您的输入中还有一个拼写错误：您有一行是 2016 年 12 月的保单 ID 1，而您的意思是 2015 年 12 月。我打算编辑您的 post 以更正它，但后来我意识到您 post 编辑的图像基于错误的数据（有错字）。如果我只在 INSERT 语句中更改它，那么它们将与图像不匹配...

如何根据另一列计算以下 n 行的平均值 - SQL (Oracle) - 先前回答问题的更新版本

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