将值从总行拆分到其他多行，直到总和达到总行的值

Question

DB Fiddle

CREATE TABLE inbound (
id SERIAL PRIMARY KEY,
campaign VARCHAR,
expected_inbound_date DATE,
expected_inbound_quantity DECIMAL,
received_inbound_quantity DECIMAL
);
INSERT INTO inbound
(campaign, expected_inbound_date, expected_inbound_quantity, received_inbound_quantity)
VALUES 
('C001', '2022-05-03', '500', '0'),
('C001', '2022-05-03', '800', '0'),
('C001', '2022-05-03', '400', '0'),
('C001', '2022-05-03', '200', '0'),
('C001', NULL, '0', '700'),
('C002', '2022-08-20', '3000', '0'),
('C002', '2022-08-20', '5000', '0'),
('C002', '2022-08-20', '2800', '0'),
('C002', NULL, '0', '4000');

预期结果

campaign |  expected_inbound_date |  expected_inbound_quantity  |  split_received_inbound_quantity
---------|------------------------|-----------------------------|----------------------------------
C001   |        2022-05-03      |             200             |          200
C001   |        2022-05-03      |             400             |          400
C001   |        2022-05-03      |             500             |          100
C001   |        2022-05-03      |             800             |            0
C001   |                        |                             |          700
---------|------------------------|-----------------------------|----------------------------------
C002   |       2022-08-20       |           3.800             |         3.800
C002   |       2022-08-20       |           5.000             |           200
C002   |       2022-08-20       |           2.800             |             0
C002   |                        |                             |         4.000

---

我想将received_inbound_quantity分割到expected_inbound_quantity的每一行，直到达到received_inbound_quantity的总和

SELECT 
i.campaign AS campaign,
i.expected_inbound_date AS expected_inbound_date,
i.expected_inbound_quantity AS expected_inbound_quantity,
i.received_inbound_quantity AS split_received_inbound_quantity
FROM inbound i
GROUP BY 1,2,3,4
ORDER BY 1,2,3,4;

我不知道如何做到这一点
你知道吗？

Answer 1

我提出了以下内容：

select i.campaign, i.expected_inbound_date, i.expected_inbound_quantity, i.received_inbound_quantity, (
select greatest(
least(
i.expected_inbound_quantity, 
(select sum(iii.received_inbound_quantity) from inbound iii where i.campaign = iii.campaign) - 
(
select cum_sum
from (
select sum(ii.expected_inbound_quantity) over (partition by ii.campaign order by ii.expected_inbound_date, ii.expected_inbound_quantity, ii.received_inbound_quantity rows between unbounded preceding and 1 preceding) cum_sum, ii.campaign, ii.expected_inbound_date, ii.expected_inbound_quantity, ii.received_inbound_quantity
from inbound ii
) tmp
where (tmp.campaign, tmp.expected_inbound_date, tmp.expected_inbound_quantity, tmp.received_inbound_quantity) = (i.campaign, i.expected_inbound_date, i.expected_inbound_quantity, i.received_inbound_quantity)
)
),
0
)
) split
from inbound i
order by i.campaign, i.expected_inbound_date, i.expected_inbound_quantity, i.received_inbound_quantity

这是一把db小提琴。

其思想是将当前行之前的行的累积和计算为cum_sum，然后选择较小的值：received_inbound_quantity的和减去cum_sum或expected_inbound_date。为了避免值<0，我使用了greatest。

Answer 2

参考这个问题的答案，解决问题的另一种方法也在redshift:中起作用

DB Fiddle

SELECT
t1.campaign AS campaign,
t1.expected_inbound_date AS expected_inbound_date,
t1.expected_inbound_quantity AS expected_inbound_quantity,
t1.received_inbound_quantity AS received_inbound_quantity,
t1.quantity_accumulated AS quantity_accumulated,
t1.quantity_total AS quantity_total,

(CASE WHEN (t1.quantity_total - t1.quantity_accumulated) >=0
THEN t1.expected_inbound_quantity ELSE

(CASE WHEN (t1.expected_inbound_quantity + t1.quantity_total - t1.quantity_accumulated) >=0
THEN (t1.expected_inbound_quantity + t1.quantity_total - t1.quantity_accumulated)
ELSE 0 END)

END) AS split
FROM
(SELECT
i.campaign AS campaign,
i.expected_inbound_date AS expected_inbound_date,
i.expected_inbound_quantity AS expected_inbound_quantity,
i.received_inbound_quantity AS received_inbound_quantity,
SUM(i.expected_inbound_quantity) OVER (PARTITION BY i.campaign ORDER BY i.expected_inbound_date, i.expected_inbound_quantity ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS quantity_accumulated,
MAX(i.received_inbound_quantity) OVER (PARTITION BY i.campaign) AS quantity_total
FROM inbound i) t1

GROUP BY 1,2,3,4,5,6
ORDER BY 1,2,3,4,5,6;