Running Total with minimum balance after modulus - sql

Question

Currently the code below does running total with 50 as its limit.
Now i would like to have 50 as the minimum value for the remaining. How could i possibly do this. Any hints will be really helpful. (min balance 50). This code is in sql 2012, need it to work sql2008 and above
Example :
- 10 10
- 20 30
- 30 60
- 40 100 --> 50 (min value of 50) 100-50 = 50
- 2 52
- 3 55
- 10 65
- 25 90
- 15 105 --> 55 (min value 50, 105-50 = 55)
- 5 60
DECLARE #Table TABLE (Id INT, ListItem INT);
INSERT INTO #Table VALUES (1, 10);
INSERT INTO #Table VALUES (2, 20);
INSERT INTO #Table VALUES (3, 30);
INSERT INTO #Table VALUES (4, 40);
INSERT INTO #Table VALUES (5, 2);
INSERT INTO #Table VALUES (6, 3);
INSERT INTO #Table VALUES (7, 10);
INSERT INTO #Table VALUES (8, 25);
INSERT INTO #Table VALUES (9, 15);
INSERT INTO #Table VALUES (10, 5);
WITH RunningTotal AS (
SELECT Id, ListItem, SUM(ListItem) OVER (ORDER BY Id) % 50 AS RT FROM #Table)
SELECT
rt.Id,
rt.ListItem,
CASE WHEN rt.RT < rt2.RT THEN rt.RT + 50 ELSE rt.RT END AS RunningTotal
FROM
RunningTotal rt
LEFT JOIN RunningTotal rt2 ON rt2.Id = rt.Id - 1
ORDER BY
rt.Id;
Edit :
Now i get the idea. But when i try to change the values, it only work once. Like say once the cumulative value exceeds 350000, deduct by 300000, meaning minimum balance is 50000.
Any hints ?
Link : http://sqlfiddle.com/#!6/c9051/1/0
Thank you.

Answer 1

The key is that when you only want to go modulo 50 when your number is above 100. This would then get you the "remainder" above 50, which you add 50 to to get your desired output
WITH RunningTotal AS (
SELECT Id, ListItem, SUM(ListItem) OVER (ORDER BY Id) AS RT FROM #Table)
SELECT Id, ListItem, RT, CASE WHEN RT > 100 THEN RT % 50 + 50 ELSE RT END AS NewRT
FROM RunningTotal