Unable to write exact sql query to get result set - sql

Question

I have below type of data set:
Base Col1 Col2 Col3
1000 0 10 1100
1100 0 10 1210
1210 0 10 1331
For deriving col3, I will use formula like
col3 = (base - col1) * (1 + col2 / 100)
If you observe above data set 1st row of col3 value is the second row base column value. And Col2 value is same for all records.
So now my problem is at later point of time my col1 (Col1 column is a part of formula) row values will update based on this i need to recalculate col3 values by using mentioned formula.
See below data set for example, if col1 value has updates then we need to recalculate col3 values like below by using formula (Col3=(base-col1)*(1+col2/100))
Base Col1 Col2 Col3
1000 10 10 1089
1089 20 10 1175.9
1175.9 30 10 1293.4
For getting above data set, I have tried like below.
SELECT
col1, col2,
col3 - SUM(col1 * (Power((1 + COL2 / 100.00), RNO)))
OVER(ORDER BY RNO ROWS UNBOUNDED PRECEDING)
FROM
(SELECT
row_number() OVER(ORDER BY col1) rno,
*
FROM
#TABLE1) A
But I am not getting the correct results.
Please use below script to create table and for populating data.
CREATE TABLE #Table1
(
[col1] INT,
[col2] INT,
[col3] INT
);
INSERT INTO #Table1
([col1],
[col2],
[col3])
VALUES (10,10, 1100),
(20,10,1210),
(30,10,1331);
Note:- In my example always base value will dependent on previous row col3 value.
Please help me.

Answer 1

You should not store calculation results in your table. This is redundant and can lead to wrong data, as you notice. Your table also lacks an order. So first thing: Give the records a timestamp or a number. Then remove Col3 and Base. (Well, you must have the initial base value of course, so either keep the base column and make all values null except for the first one or store the value somewhere else or use a fix value in your query.)
Rno Col1 Col2
1 0 10
2 0 10
3 0 10
To get the results you need a recursive query. Below query considers RNOs as adjacent (with a non-adjacent number or dates, you'd have to use row_number to number your rows first). Here I just use 1000 as the base. If this is variable, store it somewhere and take it from there.
with cte(rno, base, col1, col2, col3) as
(
select rno, 1000 as base, col1, col2, (1000 - col1) * (1 + col2/100) as col3
from mytable
where rno = 1
union all
select m.rno, cte.col3 as base, m.col1, m.col2, (cte.col3 - m.col1) * (1 + m.col2/100)
from mytable m
join cte on m.rno = cte.rno + 1
)
select * from cte
order by rno;
You can create a view for this of course.

Answer 2

When col1 changes you need to update col3 of same row,
When col3 changes you need to update Base of next row,
When Base changes you need to update col3 of same row..
and so on..
At every update of Base, col1, or col3 run this loop:
declare #i int = 1
while #i<>0 begin
update t set Col3 = newCol3
from (
select top 1 base, col1, col2, col3, (base - col1) * (1 + col2 / 100.0) newCol3
from #t
where col3 <> (base - col1) * (1 + col2 / 100.0)
order by base
) t
update t set base = newbase
from (
select top 1 base, col1, col2, col3, newbase
from (
select base, col1, col2, col3, LAG(col3,1,null) over (order by base) newbase
from #t
) t
where base <> newbase
order by base
) t
if ##ROWCOUNT=0 set #i=0
end
output
base col1 col2 col3
1000 10 10 1089
1089 20 10 1175,9
1175,9 30 10 1260,49 -- I think you have an error in your example