Running total with maximum limit - sql

Question

I have a simple question but its kinda difficult for me to solve it.
I would like to have sum up a specific column till it reached a limit and resets it self. (SQL 2012)
Lets say the limit is 50
- List item
- Value Total
- 10 10
- 20 30
- 30 60
- 40 50 (60-limit) + the current row value
- 2 2
- 3 5
- 10 15
- 25 40
- 15 55
- 5 10 (55-limit) + the current row value
Thank you very much.

Answer 1

This should do it if you have SQL Server 2012 or later:
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;
The tricky bit is allowing the numbers to overflow the 50 one time, otherwise this would be trivial.
Results are:
Id LI RunningTotal
1 10 10
2 20 30
3 30 60
4 40 50
5 2 2
6 3 5
7 10 15
8 25 40
9 15 55
10 5 10

Answer 2

create table running_totals
(
id int identity(1,1),
val int
)
insert into running_totals
select 1 union all
select 20 union all
select 10 union all
select 30 union all
select 50 union all
select 10 union all
select 11 union all
select 22 union all
select 40 union all
select 60 union all
select 20 union all
select 10 union all
select 15
declare cur_run_tot cursor for select id,val from running_totals order by id asc
declare #id int ,#val int,#runtot int
open cur_run_tot
create table #RunTot
(
id int,val int, runtot int
)
fetch next from cur_run_tot into #id,#val
while ##FETCH_STATUS = 0
begin
if #runtot is null or #runtot+#val > 50
set #runtot = #val
else
set #runtot = #runtot+ #val
insert into #RunTot
select #id,#val,#runtot
fetch next from cur_run_tot into #id,#val
end
select id as ID, val as Current_Value, runtot as Running_Total from #RunTot
drop table #RunTot
deallocate cur_run_tot