Running Deduction CTE in SQL Server using declared variable - sql

Question

Can someone please explain to me why I am dumb? I am trying to use this result set to do a running deduction from the variable I declared below. Granted I am newer at CTE's but I figured this would have been INF easier.
DECLARE #monies AS money = 35600.00;
WITH RFRoll AS
(
SELECT
col
, value
, Amt = #monies
FROM #rfTmp
UNION ALL
SELECT
col
, value
, CASE
WHEN #monies>value then #monies-value
WHEN value<#monies then #monies-value
WHEN value>#monies then #monies-#monies
END Amt
FROM #rfTmp
WHERE
CASE
WHEN #monies>value then #monies-value
WHEN value<#monies then #monies-value
WHEN value>#monies then #monies-#monies
END >0
)
SELECT *
FROM RFRoll
This is the result get I get. It looks as if its just displaying the the current line calculation instead of the running deduction I'm trying to get at.
Ive tried various different ways and I keep running into a brick wall. I keep reverting to this current state which obviously isn't correct b/c I'm not actually using a running total variable.
So I guess my question is how do i do this using a variable? Am I actually able to reset the value recursively? I don't think so? Any insight would be greatly appreciated.
The desired out out would be this (not counting the extra fourth column)
Sorry for adding the 4th column it occurred to me that maybe I haven't truly understood the issue at hand and maybe I ought to rethink my approach. Basically I want cascading deduction up until a value is equal to 0. I have to do all the comparisons b/c a value can never be negative and I cant go over the value of the variable.
I am going to try and rework this in the meantime.

Answer 1

In SQL Server 2008, you can use apply or a correlated subquery. The basic structure is:
select r.*, r2.running_value
from #rftmp r outer apply
(select sum(r2.value) as running_value
from #rftmp r2
where r2.col <= r.col
) t2;
I'm not sure if this is what you want to accomplish.
Of course, in SQL Server 2012, the function is built in using a window function with order by.

Answer 2

I figured it out, if anyone cares
declare #monies as money = 35600.00;
WITH RFRoll as
(
SELECT
#rfTmp.*
, CASE
WHEN #monies>=value then value
WHEN value<#monies then value
WHEN value>#monies then #monies
END AS Amt
, CASE
WHEN #monies>=value then value
WHEN value<#monies then value
WHEN value>#monies then #monies
END AS ValueUsed
FROM #rfTmp WHERE [No] = 1
UNION ALL
SELECT
v.*
, RFRoll.Amt + CASE
WHEN v.value>#monies-RFRoll.Amt then #monies-RFRoll.Amt
WHEN v.value<#monies-RFRoll.Amt then v.value
WHEN #monies-RFRoll.Amt>v.value then v.value
END
, CASE
WHEN v.value>#monies-RFRoll.Amt then #monies-RFRoll.Amt
WHEN v.value<#monies-RFRoll.Amt then v.value
WHEN #monies-RFRoll.Amt>v.value then v.value
END
FROM #rfTmp v INNER JOIN RFRoll ON v.[No] = RFRoll.[No] + 1
WHERE RFRoll.Amt<#monies
)
SELECT * FROM RFRoll