sql payment distribution - sql

Question

I am looking for a query where a certain amount gets distributed to each invoice below based on the account_num and item_order. Also, if partial_payment_allowed is set to 'N' then distribution of the above amount should only happen if the distributed amount is greater than the invoice_amt else it should skip the row and carry on to next invoice of the account.
Item_order inv_amount Partial_pmt account_num cr_amt
1 1256 Y 12 1000
2 1134 Y 12 1000
1 800 Y 13 1200
2 200 N 13 1200
3 156 N 13 1200
In above data, each account has a cr_amt which can be distributed according to item_order. So after distribution result would be
account_num Item_order inv_amount Partial_pmt Dist_amt Bal_amt
12 1 1256 Y 1000 256
12 2 1134 Y 256 878
13 1 800 Y 800 400
13 2 200 N 200 200
13 3 156 N 100 100
We are trying to avoid loops, any comments are highly appreciated.Thank you.

Answer 1

Extending the answer to this question:
payment distrubution oracle sql query
You can still use the SQL MODEL clause. In this version, you need separate calculations for each distinct account_num. You can achieve this using the PARTITION keyword of the SQL MODEL clause to partition by account_num.
Like this (see SQL comments for step-by-step explanation):
-- Set up test data (since I don't have your table)
WITH inv_raw (item_order, inv_amount, partial_pmt_allowed, account_num, cr_amt) AS (
SELECT 1, 1256, 'Y', 12, 1000 FROM DUAL UNION ALL
SELECT 2, 1134, 'Y', 12, 1000 FROM DUAL UNION ALL
SELECT 3, 800, 'Y', 13, 1200 FROM DUAL UNION ALL
SELECT 4, 200, 'N',13, 1200 FROM DUAL UNION ALL
SELECT 5, 156, 'N',13, 1200 FROM DUAL),
-- Ensure that the column we are ordering by is densely populated
inv_dense (dense_item_order, item_order, inv_amount, partial_pmt_allowed, account_num, cr_amt) AS
( SELECT DENSE_RANK() OVER ( PARTITION BY account_num ORDER BY item_order ), item_order, inv_amount, partial_pmt_allowed, account_num, cr_amt FROM inv_raw )
-- Give us a way to input the payment amount
--param AS ( SELECT 1100 p_payment_amount FROM DUAL )
-- The actual query starts here
SELECT
account_num,
item_order,
inv_amount,
partial_pmt_allowed,
applied dist_amount,
remaining_out balance_amt,
cr_amt
FROM inv_dense
MODEL
-- We want a completely separate calculation for each distinct account_num
PARTITION BY ( account_num )
-- We'll output one row for each value of dense_item_order.
-- We made item_order "dense" so we can do things like CV()-1 to get the
-- previous row's values.
DIMENSION BY ( dense_item_order )
MEASURES ( cr_amt, item_order, inv_amount,
partial_pmt_allowed, 0 applied,
0 remaining_in, 0 remaining_out )
RULES AUTOMATIC ORDER (
-- The amount carried into the first row is the payment amount
remaining_in[1] = cr_amt[1],
-- The amount carried into subsequent rows is the amount we carried out of the prior row
remaining_in[dense_item_order > 1] = remaining_out[CV()-1],
-- The amount applied depends on whether the amount remaining can cover the invoice
-- and whether partial payments are allowed
applied[ANY] = CASE WHEN remaining_in[CV()] >= inv_amount[CV()] OR partial_pmt_allowed[CV()] = 'Y' THEN LEAST(inv_amount[CV()], remaining_in[CV()]) ELSE 0 END,
-- The amount we carry out is the amount we brought in minus what we applied
remaining_out[ANY] = remaining_in[CV()] - applied[CV()]
)
ORDER BY account_num, item_order;