SQL Server - break down a payment correctly - sql

Question

This is the problem I am having
Example:
Total Value: £1550.00
Monthly Payments 12
This calculates at 129.16666666666666667, however you wouldn't show a money value like this, it would display as £129.17, which equals £1550.04, which is wrong
Question
Is it possible to remove the float/decimal value from 11 of the 12 installments , and only display it in the first or final payment?
Example Result
PaymentNumber Value
1 £129.00
2 £129.00
3 £129.00
4 £129.00
5 £129.00
6 £129.00
7 £129.00
8 £129.00
9 £129.00
10 £129.00
11 £129.00
12 £131.00
thanks for any help, and any suggestions of another way I could do this would be very grateful..
I have included the code for a table i am using to test this... and also added in the data below. for now using an update statement will be acceptable and i will try to make the code more efficient at a later date. I do have a procedure running that inserts the monthly breakdowns programmatically.
Table info I am using
CREATE TABLE CustomerFinance (CustomerFinanceID int identity (1,1) not null,
TotalValueOwed decimal(12,4), --1550.00
LengthOfContract int) --LENGTGH IN MONTHS, i.e. 12
CREATE TABLE CustomerFinanceLine (CustomerFinanceLineID int identity (1,1) not null,
CustomerFinanceID int, --FOREIGN KEY LINK
PaymentNumber int, --1, 2, 3 AND SO ON
PaymentValue decimal(12,4)) --THE MONTHLY BREAKDOWN COSTS
--KEYS
alter table CustomerFinance add constraint CustomerFinanceID_PK PRIMARY KEY (CustomerFinanceID)
alter table CustomerFinanceLine add constraint CustomerFinanceLineID_PK PRIMARY KEY (CustomerFinanceLineID)
alter table CustomerFinanceLine add constraint CustomerFinanceID_FK FOREIGN KEY (CustomerFinanceID) REFERENCES CustomerFinance(CustomerFinanceID)
--PaymentNumber COUNTER (RUNS IN A PROCEDURE)
CREATE PROCEDURE FinanceCounter AS
;WITH MyCTE AS
(
SELECT *,
ROW_NUMBER() OVER(PARTITION BY CustomerFinanceID ORDER BY CustomerFinanceLineID) AS NewVariation
FROM CustomerFinanceLine
)
UPDATE MyCTE
SET PaymentNumber = NewVariation
WHERE PaymentNumber IS NULL
Data
--inserted PaymentValue as null for now, ideally i will
-- have a procedure to do this and insert the breakdowns programmatically
--for now an update statement will do fine unless its easier to insert it
INSERT INTO CustomerFinance VALUES (1550.00, 12)
INSERT INTO CustomerFinanceLine VALUES (1, 1, NULL)
INSERT INTO CustomerFinanceLine VALUES (1, 2, NULL)
INSERT INTO CustomerFinanceLine VALUES (1, 3, NULL)
INSERT INTO CustomerFinanceLine VALUES (1, 4, NULL)
INSERT INTO CustomerFinanceLine VALUES (1, 5, NULL)
INSERT INTO CustomerFinanceLine VALUES (1, 6, NULL)
INSERT INTO CustomerFinanceLine VALUES (1, 7, NULL)
INSERT INTO CustomerFinanceLine VALUES (1, 8, NULL)
INSERT INTO CustomerFinanceLine VALUES (1, 9, NULL)
INSERT INTO CustomerFinanceLine VALUES (1, 10, NULL)
INSERT INTO CustomerFinanceLine VALUES (1, 11, NULL)
INSERT INTO CustomerFinanceLine VALUES (1, 12, NULL)

Answer 1

You just need to do something like
WITH T(PaymentNumber) AS
(
SELECT 1 UNION ALL
SELECT 2 UNION ALL
SELECT 3 UNION ALL
SELECT 4 UNION ALL
SELECT 5 UNION ALL
SELECT 6 UNION ALL
SELECT 7 UNION ALL
SELECT 8 UNION ALL
SELECT 9 UNION ALL
SELECT 10 UNION ALL
SELECT 11 UNION ALL
SELECT 12
)
SELECT CASE WHEN PaymentNumber < 12 THEN FLOOR(1550.00/12)
WHEN PaymentNumber = 12 THEN 1550.00 - 11*FLOOR(1550.00/12)
END
FROM T

Answer 2

Let me assume you have a list of numbers. Second, in my experience, earlier payments would be rounded up, with the final being less than that payment (your title is doing this "correctly"):
select n.n as PaymentNumber,
(case when n.n < #NumPayments then ceiling(#Amount / #NumPayments)
else #Amount - #NumPayments * ceiling(#Amount / #NumPayments)
end) as MonthlyAmount
from numbers n
where n.n <= #NumPayments;
Of course, you can do the same thing with FLOOR(). Note: this might need some adjustment for small amounts.
EDIT:
n.n is just the numbers. You can use a CTE. Here is an example:
with numbers as (
select 1 as n
union all
select n + 1
from numbers
where n < 20
)